EXHIBIT 10.28.1


                         FORM OF SECURED PROMISSORY NOTE


$________                                                          _______, 2001


         FOR VALUE RECEIVED,  this Secured Promissory Note (this "Note") is made
by  Probex  Corp.,  a  Delaware  corporation   ("Maker"),   to  ________________
("Payee"). This Note is one of the "Notes" as defined in, and is entitled to the
benefits of, that certain Security Agreement (the "Security  Agreement"),  dated
as of the date hereof.

         1.  Payments.  Maker  hereby  promises to pay to the order of Payee the
principal    sum    of     ___________________     Dollars    ($_________)    at
______________________________,  or such other place as Payee may designate from
time to time in writing,  in lawful money of the United States of America and in
immediately  available  funds,  together with  interest on the unpaid  principal
balance  hereof at the rate  provided  herein  from the date of this Note  until
payment in full of the  indebtedness  evidenced by this Note.  This Note and all
accrued  and  unpaid  interest  shall  be due and  payable  in one  lump  sum on
September 1, 2001.  Any payment  made under this Note shall be applied  first to
interest accrued and unpaid on the outstanding principal balance as of such date
of payment and then to the outstanding  principal balance due hereunder.  If any
required  payment  falls due on a  Saturday,  Sunday or a national or state bank
holiday in Texas,  then such date shall be extended to the next  succeeding  day
that is not a Saturday, Sunday or national or state bank holiday.

         2. Interest Rate. The principal  amount  outstanding  from time to time
hereunder  shall bear  interest  calculated on the basis of a 365-day year, at a
rate equal to ten percent (10%) per annum.

         3. Voluntary Prepayment. This Note may be prepaid, in whole or in part,
without premium or penalty.  All  prepayments  shall be applied first to accrued
interest and then to principal.

         4.  Mandatory  Prepayment.  Maker shall be required to prepay this Note
upon  the  cumulative  receipt  by  Maker  or its  subsidiaries  of  immediately
available  funds equal to or greater  than  $5,000,000  derived from any type of
equity and/or debt financing  benefiting Maker, other than the project financing
for the construction of Maker's initial plant facility in Wellsville, Ohio, in a
maximum  principal  amount  of  $85  million.  As  long  as  this  Note  remains
outstanding, Maker shall accept any reasonable financing proposal when presented
to Maker; provided,  however, such proposal's reasonableness is to be determined
by the majority of the voting  members of the board of directors of Maker acting
in the exercise of their business judgment.

         5. Event of Default.  An event of default  ("Event of  Default")  shall
exist if:

                  (a) Maker shall fail to pay any principal of, or any interest
on, this Note or any other amount payable under this Note,  when and as the same
shall become due and payable;

                  (b) any  representation  or warranty made or deemed made by or
on behalf of Maker in the Security  Agreement,  or any amendment or modification
thereof or waiver thereunder, or in any report, certificate, financial statement
or other document furnished pursuant to or in connection the Security Agreement,
or any amendment or modification  thereof or waiver  thereunder,  shall prove to
have been incorrect when made or deemed made;

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                  (c) Maker  shall  fail to observe  or  perform  any  covenant,
condition or agreement contained in the Security Agreement;

                  (d) Maker shall fail to make any payment (whether of principal
or  interest  and  regardless  of  amount)  in  respect  of  any   indebtedness,
individually   or  in  the   aggregate,   in  excess  of   $100,000   ("Material
Indebtedness"), when and as the same shall become due and payable;

                  (e) any event or condition occurs that results in any Material
Indebtedness  of Maker  becoming  due prior to its  scheduled  maturity  or that
enables or permits  (with or without the giving of notice,  the lapse of time or
both) the  holder or  holders  of any  Material  Indebtedness  of Maker,  or any
trustee or agent on its or their behalf,  to cause any Material  Indebtedness of
Maker to become due, or to require the  prepayment,  repurchase,  redemption  or
defeasance thereof, prior to its scheduled maturity;

                  (f)  an  involuntary  proceeding  shall  be  commenced  or  an
involuntary  petition shall be filed seeking (i) liquidation,  reorganization or
other relief in respect of Maker or its debts,  or of a substantial  part of its
assets, under any federal, state or foreign bankruptcy, insolvency, receivership
or similar law now or hereafter in effect or (ii) the appointment of a receiver,
trustee, custodian,  sequestrator,  conservator or similar official for Maker or
for a substantial part of its assets,  and, in any such case, such proceeding or
petition shall continue  undismissed for 60 days or an order or decree approving
or ordering any of the foregoing shall be entered;

                  (g) Maker shall (i)  voluntarily  commence any  proceeding  or
file any petition seeking liquidation,  reorganization or other relief under any
federal,  state or foreign bankruptcy,  insolvency,  receivership or similar law
now or  hereafter  in effect,  (ii)  consent to the  institution  of, or fail to
contest in a timely and appropriate manner, any proceeding or petition described
in clause (f) of this Section,  (iii) apply for or consent to the appointment of
a receiver,  trustee, custodian,  sequestrator,  conservator or similar official
for Maker or for a substantial part of its assets, (iv) file an answer admitting
the material  allegations of a petition filed against it in any such proceeding,
(v) make a general  assignment  for the  benefit of  creditors  or (vi) take any
action for the purpose of effecting any of the foregoing;

                  (h) Maker shall become unable,  admit in writing its inability
and fail generally to pay its debts as they become due;

                  (i) one or more  judgments  for the  payment  of  money  in an
aggregate  amount in excess of $100,000 shall be rendered  against Maker and the
same shall  remain  undischarged  for a period of thirty (30) days during  which
execution shall not be effectively  stayed, or any action shall be legally taken
by a judgment creditor to attach or levy upon any assets of Maker to enforce any
such judgment;

                  (j) any  lien  purported  to be  created  under  the  Security
Agreement  shall  cease to be, or shall be  asserted  by Maker or any  affiliate
thereof not to be, a valid and perfected  lien on the  Collateral (as defined in
the Security  Agreement),  with the priority required by the Security Agreement,
except (i) as a result of the sale or other  disposition  of the Collateral in a
transaction  permitted  under  the  Security  Agreement  or (ii) as a result  of
Payee's  failure  to  maintain  possession  of any  promissory  notes  or  other
instruments delivered to it under the applicable Security Agreement;

                  (k) there shall occur, in the reasonable  judgment of Payee, a
material adverse change in the business,  assets or prospects of Maker after the
date hereof;

                  (l) there  shall occur any  material  loss,  theft,  damage or
destruction of any of Maker's property or assets not fully covered by insurance;
or

                  (m) there shall occur a cessation of a substantial part of the
business  of Maker  for a period  which  significantly  effects  its  respective
capacity to continue its business on a profitable  basis;  or Maker shall suffer
the loss or revocation  of any license or permit now held or hereafter  acquired
by it which is necessary to the continued or lawful  operation of its respective
business;  or Maker shall be  enjoined,  restrained  or in any way  prevented by
court,  governmental or administration order from conducting all or any material

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part of its  respective  business  affairs;  or any  material  part  of  Maker's
property shall be taken through condemnation or the value of such property shall
be materially impaired through condemnation.

         6.       Remedies Upon an Event of Default.

                  (a)      Acceleration.

                           (i) If an Event of Default  described in  paragraphs
(a), (f) and (g) of Section 5 has occurred,  and at any time  thereafter  during
the  continuance  of such  event,  the Payee may  declare  the then  outstanding
amounts  hereunder to be due and payable in whole (or in part, in which case any
principal not so declared to be due and payable may thereafter be declared to be
due and  payable)  and  thereupon  the  principal  of the amounts  hereunder  so
declared to be due and payable,  together with accrued  interest thereon and all
other  obligations  of Maker  accrued  hereunder,  shall  become due and payable
immediately,  without presentment,  demand, protest or other notice of any kind,
all of which are hereby waived by Maker;

                           (ii) If any other Event of Default described in
Section 5 has occurred,  Payee shall  deliver  notice of such event to Maker and
thereupon  Maker  shall have  twenty  (20)  calendar  days to cure such Event of
Default, or Events of Default ("Cure Period").  If Maker does not cure the Event
of  Default,  or Events of  Default,  during the Cure  Period,  then at any time
thereafter  during the continuance of such event, the Payee may declare the then
outstanding  amounts  hereunder  to be due and payable in whole (or in part,  in
which case any principal not so declared to be due and payable may thereafter be
declared to be due and payable) and thereupon the principal amounts hereunder so
declared to be due and payable,  together with accrued  interest thereon and all
other  obligations  of Maker  accrued  hereunder,  shall  become due and payable
immediately,  without presentment,  demand, protest or other notice of any kind,
all of which are hereby waived by Maker.

                  (b) Remedies  Cumulative.  The remedies available to Payee, as
provided  herein,  shall  be  cumulative  and  concurrent,  and  may be  pursued
singularly,  successively or together,  at the sole discretion of Payee, and may
be exercised as often as occasion  therefor  shall arise.  No act of omission or
commission of Payee,  including  specifically any failure to exercise any right,
remedy or recourse,  shall be deemed to be a waiver or release of the same, such
waiver or release to be effected  only  through a written  document  executed by
Payee and then only to the  extent  specifically  recited  therein.  A waiver or
release with reference to any one event shall not be construed as continuing, as
a bar to, or as a waiver or release of, any subsequent right, remedy or recourse
as to a subsequent event.

         7.  Notices.  Except as otherwise  provided  for herein,  any notice or
demand which, by the provisions  hereof, is required or which may be given to or
served upon Maker or Payee shall be in writing  and,  if by  telecopy,  shall be
deemed to have been validly served,  given or delivered when  transmitted with a
copy  immediately  mailed  by  registered  or  certified  mail,  if by  personal
delivery,  shall be deemed to have been validly served,  given or delivered upon
actual  delivery  and, if mailed,  shall be deemed to have been validly  served,
given or delivered  three (3) business  days after  deposit in the United States
mails,  as  registered  or  certified  mail,  with  proper  postage  prepaid and
addressed to the party to be notified, at the addresses last given in writing by
Maker or Payee.

         8.  Successors  and Assigns.  This Note shall be binding upon Maker and
its successors and assigns (including,  without limitation, a receiver,  trustee
or debtor-in-possession of or for Maker) and shall inure to the benefit of Payee
and its  successors  and  assigns.  Maker may not assign  its  rights  hereunder
without the prior written consent of Payee, in its sole  discretion,  other than

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by operation of law. Payee may assign all or a part of its interest in this Note
or its rights hereunder to any party without the prior written consent of Maker.

         9.  GOVERNING  LAW. THIS NOTE SHALL BE DEEMED A CONTRACT AND INSTRUMENT
MADE UNDER THE LAWS OF THE STATE OF TEXAS AND  ACCEPTED  BY PAYEE IN SAID STATE,
AND ANY AND ALL  CLAIMS,  DEMANDS  OR  ACTIONS  IN ANY WAY  RELATING  THERETO OR
INVOLVING ANY DISPUTE  BETWEEN ANY OF THE PARTIES TO THIS NOTE,  WHETHER ARISING
IN CONTRACT OR TORT,  AT LAW, IN EQUITY OR  STATUTORILY,  SHALL BE CONSTRUED AND
ENFORCED IN  ACCORDANCE  WITH AND/OR  GOVERNED BY THE LAWS OF THE STATE OF TEXAS
(EXCEPTING  ITS  CHOICE  OF LAW  RULES)  AND THE LAWS OF THE  UNITED  STATES  OF
AMERICA.

         10.  Severability.  If any  provisions  of this  Note  or any  payments
pursuant to the terms  hereof shall be invalid or  unenforceable  to any extent,
the  remainder  of this  Note and any  other  payments  hereunder  shall  not be
affected  thereby and shall be enforceable to the greatest  extent  permitted by
law.  Furthermore,  in lieu of such invalid or unenforceable  provisions,  there
shall be added  automatically as part of this Note, a provision or provisions as
similar in its or their terms to such invalid or unenforceable provisions as may
be possible and be legal, valid and enforceable.

         11. No Oral Agreements. This Note and the Security Agreement as written
represent  the final  agreement  between  Maker and Payee  with  respect  to the
matters  contained herein and therein and may not be contradicted by evidence of
prior,  contemporaneous  or subsequent oral agreements  between Maker and Payee.
There are no unwritten agreements between Maker and Payee.


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         IN WITNESS  WHEREOF,  Maker has executed and delivered  this Note as of
the date and year first above written.

                                     MAKER:


                                     PROBEX CORP.,
                                     a Delaware corporation


                                     By:_________________________________
                                     Name:_______________________________
                                     Title:______________________________
























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                       Allonge to Secured Promissory Note


         _____________  ("Payee")  executes this allonge to that certain Secured
Promissory Note dated as of _______,  2001 (the "Note"), made by Probex Corp. in
favor of Payee, to provide as follows:

    1.   The following  sentence shall be added to Section 1 of the Note to read
         as follows:

         "If Maker shall not pay in full the outstanding  principal  balance and
         accrued  and  unpaid  interest  due  under  this  Note on or  prior  to
         September 1, 2001,  this Note and the accrued and unpaid  interest,  at
         the Adjusted  Interest Rate (as defined in Section 2), shall be due and
         payable in one lump sum on December 31, 2001."


    2.   The following  sentence shall be added to Section 2 of the Note to read
         as follows:

         "If the  outstanding  principal  balance  and all  accrued  and  unpaid
         interest  due  under  this  Note is not  paid in  full on or  prior  to
         September  1, 2001,  the  interest  rate on this Note shall be adjusted
         (the "Adjusted  Interest Rate")  retroactively  such that the principal
         amount  outstanding  from time to time  hereunder  shall bear  interest
         calculated  on the basis of a 365-day  year,  at a rate equal to twelve
         percent (12%) per annum."

All capitalized terms not defined herein shall have the meaning ascribed to them
in the Note.

Dated:  August ___, 2001
                                       MAKER:


                                       PROBEX CORP.


                                       By: ______________________________
                                       Name: Bruce A. Hall
                                       Title: Senior Vice President



                                       PAYEE:



                                       By: ________________________
                                       Name:_______________________
                                       Title:______________________

<PAGE>



                   Second Allonge to Secured Promissory Note


         _____________  ("Payee")  executes this allonge to that certain Secured
Promissory Note dated as of _______,  2001 (the "Note"), made by Probex Corp. in
favor of Payee, to provide as follows:

    1.   The last sentence of Section 1 of the Note,  as previously  modified by
         Allonge to  Secured  Promissory  Note,  shall be amended to read in its
         entirety as follows:

         "If Maker shall not pay in full the outstanding  principal  balance and
         accrued  and  unpaid  interest  due  under  this  Note on or  prior  to
         September 1, 2001,  this Note and the accrued and unpaid  interest,  at
         the Adjusted  Interest Rate (as defined in Section 2), shall be due and
         payable in one lump sum on January 31, 2002."


All  capitalized  terms not defined  herein shall have the meanings  ascribed to
them in the Note.

Dated:  December ___, 2001
                                         MAKER:

                                         PROBEX CORP.


                                         By:   _____________________________
                                         Name: Bruce A. Hall
                                         Title: Senior Vice President



                                         PAYEE:



                                         By:      ________________________
                                         Name:    ________________________
                                         Title:   ________________________