EXHIBIT 10.30.1


                             SECURED PROMISSORY NOTE


$500,000                                                      September 13, 2001


         FOR VALUE RECEIVED,  this Secured Promissory Note (this "Note") is made
by Probex Corp., a Delaware corporation  ("Maker"),  to Single Spur Investments,
LLC  ("Payee").  This Note is the  "Note"  defined  in, and is  entitled  to the
benefits of, that certain Security Agreement (the "Security  Agreement"),  dated
of even date herewith.

         1.  Payments.  Maker  hereby  promises to pay to the order of Payee the
principal sum of Five Hundred Thousand and no/100 Dollars  ($500,000.00) at 4757
Frank  Luke  Drive,  Addison,  Texas  75001,  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
December  31, 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  hereunder  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 twelve  percent  (12%) per  annum or,  after an Event of  Default
hereunder, eighteen percent (18%) 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 closing of project  financing for the  construction  of Maker's initial
plant facility in Wellsville, Ohio.

         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;

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

         (d) Maker or any of its  subsidiaries  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;


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         (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  indebtedness  for borrowed money of Maker or
any of its  subsidiaries,  or any  trustee or agent on its or their  behalf,  to
cause any indebtedness for borrowed money of Maker or any of its subsidiaries 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 any of its subsidiaries or their respective  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 any of its  subsidiaries  or for a
substantial part of any of their 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 or any of its subsidiaries 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 any of its subsidiaries or for a substantial part
of any of their 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 or any of its  subsidiaries  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  $25,000  shall be  rendered  against  Maker or any of its
subsidiaries 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 or any of its subsidiaries 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 or any of its
subsidiaries after the date hereof;

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

         (m) there shall occur a cessation of a substantial part of the business
of Maker or any of its subsidiaries for a period which significantly effects its
capacity to continue its business on a profitable  basis; or Maker or any of its
subsidiaries  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 or any of its subsidiaries shall
be  enjoined,  restrained  or in any way  prevented  by court,  governmental  or
administration  order from conducting all or any material part of its respective
business  affairs;  or any material part of Maker's or any of its  subsidiaries'


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property shall be taken through condemnation or the value of such property shall
be materially impaired through condemnation;

         (n)  Maker's  common  stock  shall  cease to be listed on any  national
securities  exchange or reported by the NASDAQ  National  Market System or Small
Cap Market System; or

         (o) Maker shall receive a "going concern"  opinion from its independent
auditors,  or, after giving effect to proceeds of this Note,  otherwise does not
have sufficient available working capital to ensure viability.

         6.       Remedies Upon an Event of Default.

                  (a)      Acceleration.

                  (i) If an Event of Default  described in paragraph  (f) or (g)
of  Section  5 hereof  shall  occur,  this  Note and the  obligation  to pay the
principal and accrued interest hereunder shall automatically  become immediately
due and payable without any action or notice on the part of the Payee.

                  (ii) If an Event of Default  described in paragraphs (a), (b),
(d), (e),  (h), (i), (j), (k), (l) or (m) of Section 5 hereof 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;

                  (iii) 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


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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, as set forth in the Security Agreement.

         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
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:    Bruce A. Hall
                                     Title:   Senior Vice President
























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                       Allonge to Secured Promissory Note


         Single Spur  Investments,  LLC ("Payee")  executes this allonge to that
certain  Secured  Promissory  Note dated as of September  13, 2001 (the "Note"),
made by Probex Corp. in favor of Payee, to provide as follows:

    1.   Section  1 of the Note  shall be  amended  to read in its  entirety  as
         follows:

         "1.  Payments.  Maker hereby  promises to pay to the order of Payee the
         principal sum of Five Hundred Thousand and no/100 Dollars ($500,000.00)
         at 4757 Frank Luke Drive, Addison,  Texas 75001, 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 January
         31, 2002.  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  hereunder 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."


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:   ________________________