<PAGE>
                                                                 EXHIBIT 10.6(b)


                        AMENDMENT TO SEVERANCE AGREEMENT


                  THIS AMENDMENT (this "Amendment") made this ____ day of
__________________, 2002, by and between Pennzoil-Quaker State Company, a
Delaware corporation (the "Company"), and ____________ (the "Employee").

                                    RECITALS:

                  WHEREAS, the Employee has previously entered into that certain
Severance Agreement with the Company, dated ________________________ (the
"Severance Agreement");

                  WHEREAS, the Company and the Employee desire to amend Section
2(h) of the Severance Agreement regarding any outstanding stock options upon
certain termination events.

                  NOW, THEREFORE, in consideration of the premises and mutual
covenants contained herein and for other good and valuable consideration, the
receipt of which is mutually acknowledged, effective as of the date first
written above, the Company and the Employee agree that Section 2(h) of the
Severance Agreement is hereby amended in its entirety to read as follows:

                  "(h) Stock Options. Each stock option granted to the Employee
         by the Company's former parent, Pennzoil Company (subsequently renamed
         PennzEnergy Company and now Devon Energy Corporation), prior to 1999
         and outstanding on December 30, 1998, if any, was split into two
         options, one issued by PennzEnergy Company and the other issued by the
         Company (collectively, the `Prior Options'), with each such Prior
         Option becoming fully vested as a result of the transaction occurring
         pursuant to that certain Agreement and Plan of Merger, dated as of
         April 14, 1998, among Pennzoil Company, Pennzoil Products Company,
         Downstream Merger Company and Quaker State Corporation (the
         `Transaction'). Each Prior Option will remain fully exercisable and
         outstanding until the end of its original 10-year term, subject to the
         terms and conditions of the applicable stock option agreement.

                           Stock options granted to the Employee by the Company
         on or after January 1, 1999 (the `Current Options'), to the extent
         outstanding as of the Employee's Termination Date, shall continue to
         vest during the two year period following Employee's Termination Date
         or, if earlier, until the options' expiration dates, as if Employee had
         remained employed by the Company during such two-year period. Each such
         Current Option, to the extent it is vested or becomes vested during
         such two-year period, shall be exercisable until the earlier of (1) the
         90th day following the end of such two-year period or (2) the option's
         expiration date (the `Extended Exercise Period'). Thereafter, to the
         extent not exercised during such period, the Current Options shall
         expire, terminate and be of no


                                       1
<PAGE>

         further force and effect immediately after the end of the Extended
         Exercise Period."

                  IN WITNESS WHEREOF, the Company and the Employee have executed
this Amendment as of the date first written above.

                                                PENNZOIL-QUAKER STATE COMPANY



                                                --------------------------------
                                                [NAME]
                                                [TITLE]



This Amendment is accepted
and agreed to by:



-----------------------------------
[EMPLOYEE]



                                       2