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                                                                    EXHIBIT 10.2



                                  PROBEX CORP.

                              AMENDED AND RESTATED

                            INVESTOR RIGHTS AGREEMENT


         This Amended and Restated Investor Rights Agreement (this "AGREEMENT")
is made and entered into as of June 2, 2000, by and between Probex Corp., a
Colorado corporation (the "COMPANY"), and HSB Engineering Finance Corporation, a
Delaware corporation (the "INVESTOR").

                                 R E C I T A L S

         A. The Investor has previously loaned to the Company (the "LOAN") the
aggregate amount of seven hundred fifty thousand dollars ($750,000) pursuant to
the terms and conditions set forth in that certain Convertible Loan, Warrant and
Security Agreement, dated as of June 30, 1998, by and between the Company and
the Investor (the "LOAN AGREEMENT") and the Convertible Secured Promissory Note,
dated of even date therewith (the "NOTE"), by the Company.

         B. In connection with the Loan Agreement, Investor and the Company
entered into that certain Investor Rights Agreement, dated as of June 30, 1998
(the "Original Agreement"), pursuant to which that the Investor was granted
certain rights, as more fully set forth therein.

         C. Pursuant to the Loan Agreement, Investor has the right to acquire
additional shares (as defined in the Loan Agreement, the "CONVERSION SHARES") of
the Company's Common Stock, no par value (the "COMMON STOCK"), upon the
cancellation of the outstanding principal balance on the Note and the surrender
and cancellation of the Warrant.

         D. The Investor has exercised its right to acquire the Conversion
Shares and in connection therewith, the Investor and the Company desire to amend
and restate in its entirety the terms of the Original Agreement, all as set
forth herein.

         E. Capitalized terms not otherwise defined herein shall have the
meanings given such terms in the Loan Agreement.

         NOW, THEREFORE, in consideration of the foregoing recitals, the mutual
promises hereinafter set forth, and other good and valuable consideration, the
receipt and sufficiency of which are hereby acknowledged, the parties hereto
agree as follows:

1.       INFORMATION RIGHTS.

         1.1 Information Rights. The Company covenants and agrees that,
commencing on the date of this Agreement, for so long as the Investor holds any
Conversion Shares, the Company



INVESTOR RIGHTS AGREEMENT

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will deliver to the Investor copies of the Company's Forms 10-K or 10-KSB, 10-Q
or 10-QSB, and 8-K, and Annual Reports to Shareholders, promptly after such
documents are filed with the SEC (as defined below).

2.       VOTING AGREEMENT.

         2.1 Board Representation. So long as the Investor, together with its
Affiliates (as defined in the Loan Agreement), in the aggregate, holds Common
Stock representing at least 5% of the outstanding Common Stock of the Company,
Investor will be entitled to elect one member (the "REPRESENTATIVE") of the
Company's Board of Directors (the "BOARD") and all committees thereof. The
Investor shall nominate at least two nominees for its Representative seat at
least fourteen (14) days prior to such nominee's election to the Board. For such
seat, the Company shall designate which of the two nominees shall be elected.
Upon such designation or, if at the end of such fourteen (14) day period the
Company shall have failed to designate a nominee, upon the Investor's
designation of one of the two nominees, the Company shall take, or cause to be
taken, all actions within its power to cause the Representative so designated to
be elected to the Board, including recommending to the stockholders of the
Company that they vote for the election to the Board of the individual
designated by the Investor. So long as the Investor, together with its
Affiliates, in the aggregate, holds Common Stock representing at least 5% of the
outstanding Common Stock of the Company, the Board of Directors shall take no
action to increase the number of voting directors constituting the Board of
Directors to a number greater than nine (9), without the affirmative vote of the
Representative.

         Each stockholder signatory hereto shall take all actions necessary to
vote all shares of stock entitled to vote thereon owned or held of record by
such stockholder at any annual or special meeting at which one or more directors
are elected in favor of the election as directors of the individual designated
as the Representative of the Investor. Each stockholder signatory hereto shall
take all actions by written consents in lieu of any such meeting necessary to
cause the election as director of the individual designated as Representative of
the Investors. Except as otherwise permitted in this Section 2.1, no stockholder
signatory hereto shall take any action to remove any Representative from office
as director without Cause. Any Representative may be removed as director for
Cause (as defined below) at any time by the affirmative vote of the holders of
at least a majority of the outstanding shares entitled to vote thereon. "CAUSE",
for purposes of this Article 2 only, shall mean the commission by a
Representative of a felony which in the opinion of the majority of the directors
is injurious to the business reputation of the Company or the commission by a
Representative of an act constituting the reckless disregard of his duties to
the Company, bad faith, gross negligence, willful misconduct or fraud. The
removal of any Representative as director for Cause shall not prejudice the
right of the Investor who nominated such Representative to nominate pursuant to
this Agreement a substitute director to fill the vacancy created by such
removal. Any Representative previously removed as a director for Cause shall not
be eligible thereafter to serve as a director of the Company. If a
Representative, as a result of death, disability, resignation, removal (with or
without Cause) or otherwise, cannot serve on the Board, the Investor shall
nominate an individual to fill such vacancy. Upon the nomination of a
Representative pursuant to this Section 2.1 to fill such vacancy, if, under
applicable law, such vacancy can be filled by the remaining directors, then each
director shall elect or appoint such Representative to the Board. If, under
applicable law, such vacancy cannot be filled by the remaining directors, such



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director shall take all action necessary to convene, as promptly as practicable,
an annual or special meeting of the stockholders at which the stockholders
signatory hereto shall vote all shares entitled to vote thereon owned or held of
record by such stockholder to elect such Representative to the Board.

         The Company acknowledges that the Investor will likely have, from time
to time, information that may be of interest to the Company ("INFORMATION")
regarding a wide variety of matters including, by way of example only, (1)
Investor's technologies, plans and services, and plans and strategies relating
thereto, (2) current and future investments Investor has made, may make, may
consider or may become aware of with respect to other companies and other
technologies, products and services, including, without limitation,
technologies, products and services that may be competitive with the Company's,
and (3) developments with respect to the technologies, products and services,
and plans and strategies relating thereto, of other companies, including,
without limitation, companies that may be competitive with the Company. The
Company recognizes that a portion of such Information may be of interest to the
Company. Such Information may or may not be known by the Representative. The
Company, as a material part of the consideration for this Agreement, agrees that
Investor and its Representative shall have no duty to disclose any Information
to the Company or permit the Company to participate in any projects or
investments based on any Information, or to otherwise take advantage of any
opportunity that may be of interest to the Company if it were aware of such
Information, and hereby waives, to the extent permitted by law, any claim based
on the corporate opportunity doctrine or otherwise that could limit Investor's
ability to pursue opportunities based on such Information or that would require
Investor or Representative to disclose any such Information to the Company or
offer any opportunity relating thereto to the Company.

         The Company shall, to the fullest extent permitted under applicable law
and the Company's articles of incorporation and bylaws, indemnify and hold
harmless, all of the directors, including the Representative, against any costs
or expenses (including reasonable attorneys' fees), judgments, fines, losses,
claims, damages and liabilities incurred in connection with, and amounts paid in
settlement of, any claim, action, suit, proceeding or investigation, whether
civil, criminal, administrative or investigative and wherever asserted, brought
or filed, arising out of or pertaining to any acts or omissions or alleged acts
or omissions by them in their capacities as members of the Board or any
committee thereof. The Company shall purchase or maintain in effect, if
available, directors' and officers' liability insurance covering all of the
directors, including the Representative, on terms reasonably acceptable to the
Representative, provided that the Company shall not be obligated to pay more
than $10,000 for the initial annual premium.



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INVESTOR RIGHTS AGREEMENT

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         2.2. Actions by the Board of Directors. Notwithstanding the fact that
no vote of the Board may be required, or that a lesser percentage vote may be
specified by law, by the articles of incorporation, the bylaws or otherwise, so
long as the Investor, together with its affiliates, in the aggregate, holds
Common Stock representing at least 5% of the outstanding Common Stock of the
Company, the Company shall not take any action with respect to the below listed
transactions (individually, a "SIGNIFICANT TRANSACTION"), notwithstanding the
affirmative vote of a majority of the directors, if a Representative director
and at least one other director, who is not a Representative director and not an
employee or officer (or affiliate, associate, or relative of any such employees
or officers) of the Company, votes against such Significant Transaction:

                           (i) any merger or consolidation involving the Company
                  (other than transactions involving the merger or consolidation
                  of a subsidiary with or into the Company or with or into a
                  subsidiary);

                           (ii) any sale, lease, license, exchange, transfer or
                  other disposition, directly or indirectly, in any single
                  transaction or series of related transactions of all or
                  substantially all of the assets of the Company to or with any
                  person other than into or with a subsidiary of the Company;
                  and

                           (iii) any increase or reduction of, or change in, the
                  Company's authorized stock or the creation of any additional
                  class of capital stock of the Company.

3.       REGISTRATION RIGHTS.

         3.1 Definitions. For purposes of this Section 3:

                  (a) Registration. The terms "REGISTER," "REGISTERED," and
"REGISTRATION" refer to a registration effected by preparing and filing a
registration statement in compliance with the Securities Act of 1933, as
amended, (the "SECURITIES ACT"), and the declaration or ordering of
effectiveness of such registration statement

                  (b) Registrable Securities. The term "REGISTRABLE SECURITIES"
means: (1) any Common Stock of the Company issued or to be issued (A) as
Conversion Shares and, (B) as additional shares, pursuant to that certain letter
agreement between the Company and the Investor dated as of February 25, 2000
(excluding the Conversion Shares) (the "Additional Shares"), (2) any shares of
Common Stock of the Company issued (or issuable upon the conversion or exercise
of any warrant, right or other security) as a dividend or other distribution
with respect to, or in exchange for or in replacement of, any shares of Common
Stock and the other securities described in clause (1) of this subsection (b)
and (3) any other Common Stock of the Company owned or hereafter acquired by the
Investor. Notwithstanding the foregoing, "REGISTRABLE SECURITIES" shall exclude
any Registrable Securities sold by a person in a transaction in which rights
under this Section 3 are not assigned in accordance with this Agreement or any
Registrable Securities sold in a public offering, whether sold pursuant to Rule
144 promulgated under the Securities Act, or in a registered offering, or
otherwise.



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INVESTOR RIGHTS AGREEMENT

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                  (c) Registrable Securities Then Outstanding. The number of
shares of "REGISTRABLE SECURITIES THEN OUTSTANDING" shall mean the number of
shares of Common Stock of the Company that are Registrable Securities and are
then issued and outstanding.

                  (d) Holder. For purposes of this Section 3, the term "HOLDER"
means any person signatory hereto owning of record Registrable Securities that
have not been sold to the public or pursuant to Rule 144 promulgated under the
Securities Act or any permitted assignee of record of such Registrable
Securities to whom rights under this Section 3 have been duly assigned in
accordance with this Agreement.

                  (e) SEC. The term "SEC" or "COMMISSION" means the U.S.
Securities and Exchange Commission.

         3.2.     Required Registration.

                  (a) Required Registration. After the date that the Company
becomes eligible to file a registration statement on Form S-3 (or any successor
form) in accordance with the Securities Act and the rules and regulations
promulgated thereunder (the "S-3 ELIGIBILITY DATE"), and so long as the Company
continues to be eligible to file such registration statement on Form S-3 (or any
successor form), upon the written request of the Holder, the Company shall
prepare and file a shelf registration statement on Form S-3 (or any successor
form) to effect a registration on a delayed or continuos basis with respect to
the resale of all or a part of the Registrable Securities (the "DEMAND
REGISTRABLE SECURITIES") as specified in such written notice, and the Company
will use its diligent best efforts to effect such registration (including,
without limitation, the execution of an undertaking to file post-effective
amendments, appropriate qualification under the applicable blue sky or other
state securities laws and appropriate compliance with applicable regulations
issued under the Securities Act and any other governmental requirements or
regulations) as would permit or facilitate the sale and distribution of all or
such portion of the Demand Registrable Securities of the Holder(s).

                  (b) Limitations. Notwithstanding the foregoing provisions of
this Section 3.2, the Company's obligation to effect registration of Demand
Registrable Securities under this Section 3.2 shall be subject to the following
limitations:

                           (1) The Company shall be obligated to effect only two
(2) such registrations pursuant to this Section 3.2. A registration shall not be
deemed "effected" for purpose of this Section 3.2 (i) unless it has become
effective and is maintained effective until all Demand Registrable Securities
are sold thereunder (or after the expiration of a period of ninety (90) days,
whichever is earlier), or (ii) if, after it has become effective, such
registration is interfered with by any stop order, injunction or other order or
requirement of the SEC or any other governmental agency, authority or body for
any reason other than a material misrepresentation or omission by the Holders of
Demand Registrable Securities included therein.

                           (2) The Company shall not be obligated to effect a
registration hereunder if at the time such registration is required, the Company
has material non-public information the disclosure of which, in the reasonable
business judgment of the Board, based upon advice of counsel, would have an
adverse effect on the Company; provided, however, that



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the Company shall not be permitted to delay registration under this paragraph
for a period longer than thirty (30) days without the consent of the Holders of
at least a majority of the Demand Registrable Securities.

         3.3 Piggyback Registrations. With respect to the filing of any
registration statement under the Securities Act for purposes of effecting a
public offering of securities of the Company (including, but not limited to,
registration statements relating to secondary offerings of securities of the
Company), if such registration statement is to be filed by the Company prior to
the S-3 Eligibility Date, the Company shall notify all Holders of Registrable
Securities in writing at least thirty (30) days prior to such filing and will
afford each such Holder an opportunity to include in such registration statement
all or any part of the Registrable Securities then held by such Holder. Each
Holder desiring to include in any such registration statement all or any part of
the Registrable Securities held by such Holder shall, within twenty (20) days
after receipt of the above-described notice from the Company, so notify the
Company in writing, and in such notice shall inform the Company of the number of
Registrable Securities such Holder wishes to include in such registration
statement. If a Holder decides not to include all of its Registrable Securities
in any registration statement thereafter filed by the Company, such Holder shall
nevertheless continue to have the right to include any Registrable Securities in
any subsequent registration statement or registration statements as may be filed
by the Company with respect to offerings of its securities, all upon the terms
and conditions set forth herein. Except as otherwise provided herein, there
shall be no limit on the number of times the Holders may request registration of
Registrable Securities under this Section 3.3.

                  (a) Underwriting. If a registration statement under which the
Company gives notice under this Section 3.3 is for an underwritten offering,
then the Company shall so advise the Holders of Registrable Securities. In such
event, the right of any such Holder's Registrable Securities to be included in a
registration pursuant to this Section 3.3 shall be conditioned upon such
Holder's participation in such underwriting and the inclusion of such Holder's
Registrable Securities in the underwriting to the extent provided herein. All
Holders proposing to distribute their Registrable Securities through such
underwriting shall enter into an underwriting agreement in customary form with
the managing underwriter or underwriters selected for such underwriting
(including a market stand-off agreement of up to 180 days if required by such
underwriter or underwriters). Notwithstanding any other provision of this
Agreement, if the managing underwriter(s) determine(s) in good faith that
marketing factors require a limitation of the number of shares to be
underwritten, then the managing underwriter(s) may exclude up to all Registrable
Shares that are in excess of 15% of the aggregate number of shares to be
included in such offering (including the Registrable Shares) from the
registration and the underwriting, and the number of shares that may be included
in the registration and the underwriting shall be allocated, first to the
Company, and second, to each of the Holders requesting inclusion of their
Registrable Securities in such registration statement on a pro rata basis based
on the total number of Registrable Securities then held by each such Holder;
provided, however, that the right of the underwriter(s) to exclude shares
(including Registrable Securities) from the registration and underwriting as
described above shall be restricted so that all shares that are not Registrable
Securities and are held by any other person, including, without limitation, any
person who is an employee, officer or director of the Company (or any subsidiary
of the Company), shall first be excluded from such registration and underwriting
before any Registrable Securities are so



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excluded. If any Holder disapproves of the terms of any such underwriting, such
Holder may elect to withdraw therefrom by written notice to the Company and the
underwriter(s), delivered at least ten (10) business days prior to the effective
date of the registration statement. Any Registrable Securities excluded or
withdrawn from such underwriting shall be excluded and withdrawn from the
registration. For any Holder that is a partnership, the Holder and the partners
and retired partners of such Holder, or the estates and family members of any
such partners and retired partners and any trusts for the benefit of any of the
foregoing persons, and for any Holder that is a corporation, the Holder and all
corporations that are affiliates of such Holder, shall be deemed to be a single
"Holder," and any pro rata reduction with respect to such Holder shall be based
upon the aggregate amount of shares carrying registration rights owned by all
entities and individuals included in such Holder, as defined in this sentence.

         3.4 Obligations of the Company. Whenever required to effect the
registration of any Registrable Securities under this Agreement the Company
shall, as expeditiously as reasonably possible:

                  (a) Registration Statement. Prepare and file with the SEC a
registration statement with respect to such Registrable Securities and use its
best efforts to cause such registration statement to become effective, provided,
however, that the Company shall not be required to keep any such registration
statement effective for more than ninety (90) days.

                  (b) Amendments and Supplements. Prepare and file with the SEC
such amendments and supplements to such registration statement and the
prospectus used in connection with such registration statement as may be
necessary to comply with the provisions of the Securities Act with respect to
the disposition of all securities covered by such registration statement.

                  (c) Prospectuses. Furnish to the Holders such number of copies
of a prospectus, including a preliminary prospectus, in conformity with the
requirements of the Securities Act, and such other documents as they may
reasonably request in order to facilitate the disposition of the Registrable
Securities owned by them that are included in such registration.

                  (d) Blue Sky. Use its best efforts to register and qualify the
securities covered by such registration statement under such other securities or
Blue Sky laws of such jurisdictions as shall be reasonably requested by the
Holders, provided that the Company shall not be required in connection therewith
or as a condition thereto to qualify to do business or to file a general consent
to service of process in any such states or jurisdictions.

                  (e) Underwriting. In the event of any underwritten public
offering, enter into and perform its obligations under an underwriting agreement
in usual and customary form, with the managing underwriter(s) of such offering.
Each Holder participating in such underwriting shall also enter into and perform
its obligations under such an agreement.

                  (f) Notification. Notify each Holder of Registrable Securities
covered by such registration statement at any time when a prospectus relating
thereto is required to be delivered under the Securities Act of the happening of
any event as a result of which the prospectus included in such registration
statement, as then in effect, includes an untrue statement



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of a material fact or omits to state a material fact required to be stated
therein or necessary to make the statements therein not misleading in the light
of the circumstances then existing.

                  (g) Opinion and Comfort Letter. Furnish, at the request of any
Holder requesting registration of Registrable Securities, on the date that such
Registrable Securities are delivered to the underwriter(s) for sale, if such
securities are being sold through underwriters, or, if such securities are not
being sold through underwriters, on the date that the registration statement
with respect to such securities becomes effective, (i) an opinion, dated as of
such date, of the counsel representing the Company for the purposes of such
registration, in form and substance as is customarily given to underwriters in
an underwritten public offering and reasonably satisfactory to a majority in
interest of the Holders requesting registration, addressed to the underwriters,
if any, and to the Holders requesting registration of Registrable Securities and
(ii) a "comfort" letter dated as of such date, from the independent certified
public accountants of the Company, in form and substance as is customarily given
by independent certified public accountants to underwriters in an underwritten
public offering and reasonably satisfactory to a majority in interest of the
Holders requesting registration, addressed to the underwriters, if any, and to
the Holders requesting registration of Registrable Securities.

                  (h) Exchange Listing. Cause the Registrable Securities to be
authorized for listing on the securities exchange on which securities of the
same class of the Company are then primarily listed.

         3.5 Furnish Information. It shall be a condition precedent to the
obligations of the Company to take any action pursuant to Sections 3.2 or 3.3
that the selling Holders shall furnish to the Company such information regarding
themselves, the Registrable Securities held by them, and the intended method of
disposition of such securities as shall be required to timely effect the
Registration of their Registrable Securities.

         3.6 Indemnification. In the event any Registrable Securities are
included in a registration statement under Sections 3.2 or 3.3:

                  (a) By the Company. To the extent permitted by law; the
Company will indemnify and hold harmless each Holder, the partners, officers and
directors of each Holder, any underwriter (as determined in the Securities Act)
for such Holder and each person, if any, who controls such Holder or underwriter
within the meaning of the Securities Act or the Securities Exchange Act of 1934,
as amended, (the "1934 ACT"), against any losses, claims, damages, or
Liabilities (joint or several) to which they may become subject under the
Securities Act, the 1934 Act or other federal or state law, insofar as such
losses, claims, damages, or liabilities (or actions in respect thereof) arise
out of or are based upon any of the following statements, omissions or
violations (collectively a "VIOLATION"):

                           (i) any untrue statement or alleged untrue statement
                  of a material fact contained in such registration statement,
                  including any preliminary prospectus or final prospectus
                  contained therein or any amendments or supplements thereto;



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                           (ii) the omission or alleged omission to state
                  therein a material fact required to be stated therein, or
                  necessary to make the statements therein not misleading, or

                           (iii) any violation or alleged violation by the
                  Company of the Securities Act, the 1934 Act, any federal or
                  state securities law or any rule or regulation promulgated
                  under the Securities Act, the 1934 Act or any federal or state
                  securities law in connection with the offering covered by such
                  registration statement;

and the Company will reimburse each such Holder, partner, officer or director,
underwriter or controlling person for any legal or other expenses reasonably
incurred by them, as incurred, in connection with investigating or defending any
such loss, claim, damage, liability or action; provided, however, that the
indemnity agreement contained in this subsection 3.6(a) shall not apply to
amounts paid in settlement of any such loss, claim, damage, liability or action
if such settlement is effected without the consent of the Company (which consent
shall not be unreasonably withheld), nor shall the Company be liable in any such
case for any such loss, claim, damage, liability or action to the extent that it
arises out of or is based upon a Violation which occurs in reliance upon and in
conformity with written information furnished expressly for use in connection
with such registration by such Holder, partner, officer, director, underwriter
or controlling person of such Holder.

                  (b) By Selling Holders. To the extent permitted by law, each
selling Holder will indemnify and hold harmless the Company, each of its
directors, each of its officers who have signed the registration statement, each
person, if any, who controls the Company within the meaning of the Securities
Act, any underwriter and any other Holder selling securities under such
registration statement or any of such other Holder's partners, directors or
officers or any person who controls such Holder within the meaning of the
Securities Act or the 1934 Act, against any losses, claims, damages or
liabilities (joint or several) to which the Company or any such director,
officer, controlling person, underwriter or other such Holder, partner or
director, officer or controlling person of such other Holder may become subject
under the Securities Act, the 1934 Act or other federal or state law, insofar as
such losses, claims, damages or liabilities (or actions in respect thereto)
arise out of or are based upon any Violation, in each case to the extent (and
only to the extent) that such Violation occurs in reliance upon and in
conformity with written information furnished by such Holder expressly for use
in connection with such registration; and each such Holder will reimburse any
legal or other expenses reasonably incurred by the Company or any such director,
officer, controlling person, underwriter or other Holder, partner, officer,
director or controlling person of such other Holder in connection with
investigating or defending any such loss, claim, damage, liability or action:
provided, however, that the indemnity agreement contained in this subsection
3.6(b) shall not apply to amounts paid in settlement of any such loss, claim,
damage, liability or action if such settlement is effected without the consent
of the Holder, which consent shall not be unreasonably withheld; and provided,
further, that the total amounts payable in indemnity by a Holder under this
Section 3.6(b) in respect of any Violation shall not exceed the net proceeds
received by such Holder in the registered offering out of which such Violation
arises.



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                  (c) Notice. Promptly after receipt by an indemnified party
under this Section 3.6 of notice of the commencement of any action (including
any governmental action), such indemnified party will, if a claim in respect
thereof is to be made against any indemnifying party under this Section 3.6,
deliver to the indemnifying party a written notice of the commencement thereof
and the indemnifying party shall have the right to participate in, and, to the
extent the indemnifying party so desires, jointly with any other indemnifying
party similarly noticed, to assume the defense thereof with counsel mutually
satisfactory to the parties; provided, however, that an indemnified party shall
have the right to retain its own counsel, with the fees and expenses to be paid
by the indemnifying party, if representation of such indemnified party by the
counsel retained by the indemnifying party would be inappropriate due to actual
or potential conflict of interests between such indemnified party and any other
party represented by such counsel in such proceeding. The failure to deliver
written notice to the indemnifying party within a reasonable time of the
commencement of any such action shall relieve such indemnifying party of
liability to the indemnified party under this Section 3.6 to the extent the
indemnifying party is prejudiced as a result thereof, but the omission so to
deliver written notice to the indemnified party will not relieve it of any
liability that it may have to any indemnified party otherwise than under this
Section 3.6.

                  (d) Defect Eliminated in Final Prospectus. The foregoing
indemnity agreements of the Company and Holders are subject to the condition
that, insofar as they relate to any Violation made in a preliminary prospectus
but eliminated or remedied in the amended prospectus on file with the SEC at the
time the registration statement in question becomes effective or the amended
prospectus filed with the SEC pursuant to SEC Rule 424(b) (the "FINAL
PROSPECTUS"), such indemnity agreement shall not inure to the benefit of any
person if a copy of the Final Prospectus was timely furnished to the indemnified
party and was not furnished to the person asserting the loss, liability, claim
or damage at or prior to the time such action is required by the Securities Act.

                  (e) Contribution. In order to provide for just and equitable
contribution to joint liability under the Securities Act in any case in which
either (i) any Holder exercising rights under this Agreement, or any controlling
person of any such Holder, makes a claim for indemnification pursuant to this
Section 3.6 but it is judicially determined (by the entry of a final judgment or
decree by a court of competent jurisdiction and the expiration of time to appeal
or the denial of the last right of appeal) that such indemnification may not be
enforced in such case notwithstanding the fact that this Section 3.6 provides
for indemnification in such case, or (ii) contribution under the Securities Act
may be required on the part of any such selling Holder or any such controlling
person in circumstances for which indemnification is provided under this Section
3.6; then, and in each such case, the Company and such Holder will contribute to
the aggregate losses, claims, damages or liabilities to which they may be
subject (after contribution from others) in such proportion so that such Holder
is responsible for the portion represented by the percentage that the public
offering price of its Registrable Securities offered by and sold under the
registration statement bears to the public offering price of all securities
offered by and sold under such registration statement, and the Company and other
selling Holders are responsible for the remaining portion; provided, however,
that, in any such case: (A) no such Holder will be required to contribute any
amount in excess of the public offering price of all such Registrable Securities
offered and sold by such Holder pursuant to such registration statement;



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and (B) no person or entity guilty of fraudulent misrepresentation (within the
meaning of Section 11(f) of the Securities Act) will be entitled to contribution
from any person or entity who was not guilty of such fraudulent
misrepresentation.

                  (f) Survival. The obligations of the Company and Holders under
this Section 3.5 shall survive until the fifth anniversary of the completion of
any offering of Registrable Securities in a registration statement, regardless
of the expiration of any statutes of limitation or extensions of such statutes.

         3.7 Expenses. All expenses incurred in connection with a registration
pursuant to Sections 3.2 and 3.3 (excluding underwriters' and brokers' discounts
and commissions relating to shares sold by the Holders and legal fees of counsel
for the Holders), including, without limitation all federal and "blue sky"
registration, filing and qualification fees, printers' and accounting fees, and
fees and disbursements of counsel for the Company, shall be borne by the
Company.

         3.8 Termination of the Company's Obligations. The Company shall have no
obligations pursuant to Sections 3.2 or 3.3 with respect to any Registrable
Securities proposed to be sold by a Holder in a registration pursuant to
Sections 3.2 or 3.3 more than five (5) years after the date of this Agreement,
or, if, in the opinion of counsel to the Company, all such Registrable
Securities proposed to be sold by a Holder may then be sold under Rule 144 in
one transaction without exceeding the volume limitations thereunder.

         3.9 No Registration Rights to Third Parties. Without the prior written
consent of the Holders of a majority in interest of the Registrable Securities
then outstanding, the Company covenants and agrees that it shall not grant, or
cause or permit to be created, for the benefit of any person or entity any
registration rights of any kind (whether similar to the registration rights
described in this Article 3, or otherwise) relating to shares of the Company's
Common Stock or any other voting securities of the Company, other than rights
that are on a parity with or subordinate in right to the Investor.

4.       [INTENTIONALLY OMITTED]

5.       TERMINATION OF PRIOR AGREEMENTS.

         5.1 Termination of Loan Agreement and Warrant. The parties acknowledge
that the Investor has exercised its right to receive the Conversion Shares,
constituting 2,609,347 shares of Common Stock, in exchange for cancellation of
the Outstanding Balance and surrender and cancellation of the Warrant. As a
result, all of the terms and conditions of the Loan Agreement having been
satisfied, and the Warrant having been surrendered and cancelled, the parties
hereby acknowledge that all of the parties to the Loan Agreement and Warrant
have fully performed their respective obligations thereunder (except for the
obligations of the Investor under Section 4.5 of the Loan Agreement, which
obligations are not yet due as of the date of this Agreement) and that there are
no violations or breaches of any of the terms of such agreements known to any of
the parties. The parties further affirm that, effective upon the execution and
delivery of this Agreement, the Loan Agreement and the Warrant are hereby
terminated and cancelled, and the



                                       11
INVESTOR RIGHTS AGREEMENT

<PAGE>   12

terms and provisions thereof shall have no further force or effect (with the
sole exception of Section 4.5 of the Loan Agreement which shall survive the
termination thereof).

         5.2 Termination of Original Agreement. The parties acknowledge that the
Company has issued to the Investor the Additional Shares, constituting an
aggregate of 186,767 shares of Common Stock. In connection therewith, the
parties hereby acknowledge that there are no violations or breaches of any of
the terms of the Original Agreement known to any of the parties, and further
affirm that, effective upon the execution and delivery of this Agreement, the
Original Agreement is hereby terminated and cancelled, and except as expressly
amended and restated in this Agreement, the terms and provisions thereof shall
have no further force or effect.

6.       ASSIGNMENT AND AMENDMENT.

         6.1 Assignment. Notwithstanding anything herein to the contrary, the
rights of the Investor may be assigned to any transferee of shares of Common
Stock held by the Investor, except that the rights of Investor pursuant to
Section 2.2 may only be assigned to an Affiliate of the Investor.

         6.2 Amendment of Rights. Any provision of this Agreement may be amended
and the observance thereof may be waived (either generally or in a particular
instance and either retroactively or prospectively), only with the written
consent of the Company and Investor (or, in the case of an amendment or waiver
of any provision of Section 3 hereof), only with the written consent of the
Company and the Holders of a majority of the Registrable Securities then
outstanding and entitled to the registration rights set forth in Section 3
hereof. Any amendment or waiver effected in accordance with this Section 6.2
shall be binding upon the Investor, each Holder, each permitted successor or
assignee of such Investor or Holder and the Company.

7.       CONFIDENTIALITY.

         7.1 Protection of Confidential Information. Confidential or proprietary
information disclosed by either party under this Agreement shall be considered
confidential information (the "CONFIDENTIAL INFORMATION") and shall not be
disclosed by the Company or Investor to any third party. The Company or Investor
shall immediately notify the other party of any information that comes to its
attention which might indicate that there has been a loss of confidentiality
with respect to the Confidential Information. In the event that the Company or
Investor is requested or becomes legally compelled (by statute or regulation or
by oral questions, interrogatories, request for information or documents,
subpoena, criminal or civil investigative demand or similar process, including
without limitation, in connection with any public or private offering of the
Company's capital stock) to disclose any of the Confidential Information, such
party (the "DISCLOSING PARTY") shall provide the other party (the
"NON-DISCLOSING PARTY") with prompt written notice of that fact so that the
other party may seek (with the cooperation and reasonable efforts of the
Disclosing Party) a protective order, confidential treatment or other
appropriate remedy. In such event, the Disclosing Party shall furnish only that
portion of the Confidential Information which is legally required and shall
exercise reasonable efforts to obtain reliable assurance that confidential
treatment will be accorded the Confidential Information to the extent reasonably
requested by the Non-Disclosing Party. The provisions of this Section 7.1 shall
be in



                                       12
INVESTOR RIGHTS AGREEMENT

<PAGE>   13

addition to, and not in substitution for, the provisions of any separate
nondisclosure agreement executed by the parties hereto with respect to the
transaction contemplated hereby.

         7.2 Disclosure of Terms; Press Releases. Notwithstanding the provisions
of Section 7.1 above, from and after the Effective Date, the Company may
disclose the existence and terms of this Agreement and Investor's investment in
the Company solely (i) to the Company's investors, investment bankers, lenders,
accountants, legal counsel, business partners, and bona fide prospective
investors, employees, lenders and business partners, in each case only where
such persons or entities have agreed not to disclose such information to any
third party, and (ii) to the extent necessary for the Company to comply with any
of its disclosure and reporting obligations under applicable securities laws and
regulations, and the rules and regulations of any applicable securities
exchange. The Company shall not issue any press release or make any other
announcement to the general public or in any professional or trade publication
regarding Investor, this Agreement or any of the terms hereof without the prior
consent of Investor, which consent shall be in the sole discretion of Investor,
except for any press release or other announcement required pursuant to clause
(ii) above, in which case, such consent may not be unreasonably withheld or
delayed. Notwithstanding the foregoing, Investor may disclose its investment in
the Company and the terms thereof to third parties or to the public at its
discretion, and the Company shall have the right to disclose to third parties
any such information disclosed by Investor in a press release or other public
announcement without the prior consent of Investor. If the Company or Investor
determines that any disclosure not otherwise authorized by this Agreement is
required by law or regulation, then the provisions of Section 7.1 regarding
disclosure of Confidential Information by a Disclosing Party shall govern.

8.       GENERAL PROVISIONS.

         8.1. Notices. Except as may be otherwise provided herein, all notices,
requests, waivers and other communications made pursuant to this Agreement shall
be in writing and shall be conclusively deemed to have been duly given (a) when
hand delivered to the other party; (b) when received when sent by facsimile at
the address and number set forth below, provided that the sending party receives
written confirmation of receipt; (c) three business days after deposit in the
U.S. mail with first class or certified mail receipt requested postage prepaid
and addressed to the other party as set forth below; or (d) the next business
day after deposit with a national overnight delivery service, postage prepaid,
addressed to the parties as set forth below with next-business-day delivery
guaranteed, provided that the sending party receives a confirmation of delivery
from the delivery service provider.



                                       13
INVESTOR RIGHTS AGREEMENT

<PAGE>   14

                           To Investor:

                           HSB Engineering Finance Corporation
                           One State Street
                           Hartford, CT  06102
                           Attn:  John McManus, Vice President
                           Fax:  (860) 722-5710
                           Tel:  (860) 722-5444

                           With copies to:

                           Gibson, Dunn & Crutcher LLP
                           333 South Grand Avenue
                           Los Angeles, CA  90071-3197
                           Attn:  Bradford P. Weirick, Esq.
                           Fax:  (213) 229-7520
                           Tel:  (213) 229-7765

                           To the Company:

                           Probex Corp.
                           1467 LeMay, Suite 111
                           Carrollton, Texas  75007
                           Attn:  Thomas G. Plaskett, Chief Executive Officer
                           Fax:  (972) 466-1556
                           Tel:  (972) 466-1555

                           with copies to:

                           Jenkens & Gilchrist, P.C.
                           1445 Ross Ave., Suite 3200
                           Dallas, TX  75202-2799
                           Attn:  Robert W. Dockery, Esq.
                           Fax:  (214) 855-4300
                           Tel:  (214) 855-4163

                  Each person making a communication hereunder by facsimile
shall promptly confirm by telephone to the person to whom such communication was
addressed each communication made by it by facsimile pursuant hereto but the
absence of such confirmation shall not affect the validity of any such
communication. A party may change or supplement the addresses given above, or
designate additional addresses, for purposes of this Section 8.1 by giving the
other party written notice of the new address in the manner set forth above.

         8.2 Entire Agreement. This Agreement constitutes and contains the
entire agreement and understanding of the parties with respect to the subject
matter hereof and supersedes any and all prior negotiations, correspondence,
agreements, understandings, duties or obligations between



                                       14
INVESTOR RIGHTS AGREEMENT

<PAGE>   15

the parties respecting the subject matter hereof, including expressly the
Original Agreement, the Loan Agreement and the Warrant.

         8.3 Governing Law. This Agreement shall be governed by and construed
exclusively in accordance with the internal laws of the State of Connecticut as
applied to agreements entered into and to be performed entirely within
Connecticut, excluding that body of law relating to conflict of laws and choice
of law.

         8.4 Severability. If one or more provisions of this Agreement are held
to be unenforceable under applicable law, then such provision(s) shall be
excluded from this Agreement and the balance of this Agreement shall be
interpreted as if such provision(s) were so excluded and shall be enforceable in
accordance with its terms.

         8.5 Third Parties. Nothing in this Agreement, express or implied, is
intended to confer upon any person, other than the parties hereto and their
permitted successors and assigns, any rights or remedies under or by reason of
this Agreement.

         8.6 Successors and Assigns. Subject to the provisions of Section 6.1,
the provisions of this Agreement shall inure to the benefit of, and shall be
binding upon, the successors and permitted assigns of the parties hereto.

         8.7 Captions. The captions to sections of this Agreement have been
inserted for identification and reference purposes only and shall not be used to
construe or interpret this Agreement.

         8.8 Counterparts. This Agreement may be executed in counterparts, each
of which shall be deemed an original, but all of which together shall constitute
one and the same instrument.

         8.9 Adjustments for Stock Splits, Etc. Wherever in this Agreement there
is a reference to a specific number of shares of Common Stock of the Company,
then, upon the occurrence of any subdivision, combination or stock dividend of
Common Stock, the specific number of shares so referenced in this Agreement
shall automatically be proportionally adjusted to reflect the affect on the
outstanding shares of such class or series of stock by such subdivision,
combination or stock dividend.

         8.10 Sections. References to a "section" when used without further
attribution shall refer to the particular sections of this Agreement.

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INVESTOR RIGHTS AGREEMENT

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         IN WITNESS WHEREOF, the parties hereto have executed this Agreement as
of the date and year first above written.

PROBEX CORP.,                               HSB ENGINEERING FINANCE CORPORATION,
A COLORADO CORPORATION                      A DELAWARE CORPORATION

By: /s/ BRUCE A. HALL                       By: /s/ MARY P. SCHMITT
    ---------------------------------           --------------------------------

Name: Bruce A. Hall                         Name: Mary P. Schmitt
      -------------------------------             ------------------------------

Title: Senior Vice President & Chief
       Financial Officer                    Title: Assistant Vice President
       ------------------------------              -----------------------------


SHAREHOLDERS:

/s/ ALEX D. DASPIT
--------------------------------
Alex D. Daspit

/s/ MARTIN R. MACDONALD
--------------------------------
Martin R. MacDonald

/s/ THOMAS G. MURRAY
--------------------------------
Thomas G. Murray



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INVESTOR RIGHTS AGREEMENT