<PAGE>

                                                                    Exhibit 10.8

                     Sunoco, Inc. Executive Incentive Plan
                      Amendment Effective August 1, 2000
                      ----------------------------------

  Effective August 1, 2000, the Sunoco, Inc. Executive Incentive Plan (the
"Plan") is hereby amended as follows:

     (1)  the following text is inserted as a new Section 1.27 in the Plan, and
  the remaining Sections of Article I of the Plan are sequentially re-numbered,
  as appropriate:

          "1.27  Pro-rated Bonus Award - shall mean an amount equal to the
     respective Incentive Award otherwise payable to a Participant for the Plan
     Year in which the Participant's termination of employment with the Company
     (other than for Just Cause) is effective, multiplied by a fraction the
     numerator of which is the number of full and partial months in the
     applicable Plan Year through the date of termination of such Participant's
     employment, and the denominator of which is twelve (12)."

     (2)  the current text of subsection 5.1 ("Forfeiture") of the Plan is
  deleted in its entirety, and the following text is inserted in lieu thereof:

          "5.1  Forfeiture.  If a Participant's employment with the Company is
     terminated for Just Cause before March 1 after the performance year, such
     Participant will not receive an award for the preceding Plan Year."

     (3)  the current text of subsection 5.2 ("Proration") of the Plan is
  deleted in its entirety, and the following text is inserted in lieu thereof:

          "5.2  Proration.  A Pro-rated Bonus Award, reflecting participation
     for a portion of the Plan Year, will be paid to any Participant whose
     employment status changed during the year as a result of death or permanent
     disability (as determined by the Committee), or due to retirement, approved
     leave of absence, or termination at the Company's request (other than for
     Just Cause). New hires and part-time employees also will receive a prorated
     award. Unless otherwise required by applicable law, any prorated award
     payable hereunder will be paid on the date when Incentive Awards are
     otherwise payable as provided in the Plan."
<PAGE>

                     Sunoco, Inc. Executive Incentive Plan
                     Amendment Effective November 1, 2000
                     ------------------------------------

  Effective November 1, 2000, the Sunoco, Inc. Executive Incentive Plan (the
"Plan") is hereby amended as follows:

     (1)  the following new Section 1.5 ("CIC Just Cause") is added, and the
  subsequent sections of the Plan are re-numbered sequentially:

          "1.5      CIC Just Cause - shall mean:
                    (a)  a judicial determination that the Participant has
               committed fraud, misappropriation, or embezzlement against the
               Company; or
                    (b)  a non-appealable conviction of, or entry of a plea of
               nolo contendere for, an act by the Participant constituting a
               felony which, as determined by the Company in good faith,
               constitutes a crime involving moral turpitude and has resulted in
               material harm to the Company, its subsidiaries and affiliates
               taken as a whole.
               A termination of employment pursuant to Just Cause shall not be
          effective unless accompanied by a copy of a resolution duly adopted by
          the affirmative vote of not less a majority of the Continuing
          Directors at a meeting of the Board of Directors which was called and
          held for the purpose of considering such termination, or if there are
          no Continuing Directors, when by at least three quarters (3/4) of the
          entire Board of Directors (after reasonable notice to the Participant
          and an opportunity for the Participant, together with the
          Participant's counsel, to be heard before the Board of Directors)
          finding that, in the good faith opinion of the Board of Directors, the
          Participant was guilty of conduct set forth in the preceding sentence,
          and specifying the particulars thereof in detail. In any Board
          deliberations or votes concerning a determination under this Section
          1.5, the Participant shall recuse himself from such deliberations and
          votes."

     (2)  the current Section 1.5 ("CIC Participant") is deleted in its
  entirety, and replaced with the following text:

          1.6  CIC Participant - shall mean any Participant who:
                    (a)  was employed by the Company on the date of the Change
               in Control;
                    (b)  was eligible for a prorated award under the provisions
               of Section 5.2; or
                    (c)  following a Potential Change in Control, ceased to be
               an employee of the Company as a result of either a termination of
               employment by the Company other than for CIC Just Cause or a
               termination of employment by the Participant for one of the
               following reasons:
                         (1)  The assignment to such Participant of any duties
                    materially inconsistent with such Participant's positions,
                    duties, responsibilities and status with the Company
                    immediately prior to the Change in Control, or a reduction
                    in the duties and responsibilities held by the Participant
                    immediately prior to the Change in Control; a change in the
                    Participant's reporting responsibilities, title or offices
                    as in effect immediately prior to the Change in Control that
                    is adverse to the Participant; or any removal of the
                    Participant from or any failure to re-elect the Participant
                    to any position
<PAGE>

                    with the Company that such Participant held immediately
                    prior to the Change in Control except in connection with
                    such Participant's:
                              (i)  assignment to a new position at a higher
                         combined annual base salary and Guideline Incentive
                         Award; or
                              (ii) termination of employment by the Company for
                         CIC Just Cause; or
                         (2)  With respect to any Participant who is a member of
                    the Board of Directors immediately prior to the Change in
                    Control, any failure of the shareholders of the Company to
                    elect or reelect, or of the Company to appoint or reappoint,
                    the Participant as a member of the Board of Directors;
                         (3)  A reduction by the Company in the Participant's
                    annual base salary or Guideline Incentive Award as in effect
                    immediately prior to the Change in Control; the failure by
                    the Company to continue in effect, or the taking of any
                    action by the Company that would adversely affect such
                    Participant's participation in or materially reduce such
                    Participant's benefits under its employee benefit plans or
                    compensation plans, taken as a whole, in which such
                    Participant was participating immediately prior to the
                    Change in Control; provided, however, that in the aggregate
                    such actions by the Company significantly reduce the
                    Participant's total compensation (i.e., the sum of
                    Participant's annual base salary, Guideline Incentive Award
                    and the aggregate value to the Participant of all employee
                    benefit and compensation plans); or the failure by the
                    Company, without the Participant's consent, to pay to the
                    Participant any portion of the Participant's current
                    compensation, or to pay to the Participant any portion of an
                    installment of deferred compensation under any deferred
                    compensation program of the Company; or
                         (4)  The Company requires the Participant to be based
                    anywhere other than the Participant's present work location
                    or a location within thirty-five (35) miles from the present
                    location; or the Company requires the Participant to travel
                    on Company business to an extent substantially more
                    burdensome than such Participant's travel obligations during
                    the period of twelve (12) consecutive months immediately
                    preceding the Change in Control; provided, however, that the
                    Participant can demonstrate that such termination or
                    circumstance in subsections (1) through (4) herein leading
                    to termination was at the request of a third party with
                    which the Company had entered into negotiations or an
                    agreement with regard to a Change in Control or otherwise
                    occurred in connection with, or in anticipation of, a Change
                    in Control, and also provided that in either such case, such
                    Change in Control actually occurs within one (1) year
                    following the date of termination."

  (3) the current Section 1.8 ("Common Stock Unit") is deleted in its entirety,
and the subsequent sections of the Plan are re-numbered sequentially;
<PAGE>

  (4) the following new Section 1.8 ("Code") is added, and the subsequent
sections of the Plan are re-numbered sequentially:

          "1.8 Code - shall mean the Internal Revenue Code of 1986, as amended."

  (5) the current Section 1.11 ("Compensation Committee") is deleted in its
entirety, and replaced with the following text:

          "1.9  Committee - shall mean the committee appointed to administer
      this Plan by the Board of Directors of the Company, as constituted from
      time to time. The Committee shall consist of at least two (2) members of
      the Board of Directors, each of whom shall meet applicable requirements
      set forth in the pertinent regulations under Section 16 of the Securities
      Exchange Act of 1934, as amended, and Section 162(m) of the Code."

  (6) the following new Section 1.15 ("Fair Market Value") is added, and the
subsequent sections of the Plan are re-numbered sequentially:

          "1.15  Fair Market Value - shall mean, as of any date and in respect
      of any share of Sunoco Stock, the opening price on such date of a share of
      Sunoco Stock (which price shall be the closing price on the previous
      trading day of a share of Sunoco Stock as reported on the New York Stock
      Exchange Composite Transactions Tape, and as reflected in the consolidated
      trading tables of the Wall Street Journal or any other publication
      selected by the Committee). If there is no sale of shares of Sunoco Stock
      on the New York Stock Exchange for more than ten (10) days immediately
      preceding such date, or if deemed appropriate by the Committee for any
      other reason, the fair market value of the shares of Sunoco Stock shall be
      as determined by the Committee in such other manner as it may deem
      appropriate. In no event shall the fair market value of any share of
      Sunoco Stock be less than its par value."

  (7) the following new Section 1.19 ("Ordinary Just Cause") is added, and the
subsequent sections of the Plan are re-numbered sequentially:

      "1.19  Ordinary Just Cause - shall mean:
            (a) the Participant's conviction for a criminal offense (other than
          a traffic offense) including, without limitation, a crime involving
          moral turpitude or common law fraud; or
            (b) the Company's reasonable determination that the Participant has:
                (1) committed an act of fraud, embezzlement, theft, or
            misappropriation of funds in connection with such Participant's
            duties in the course of his employment with the Company; or
                (2) engaged in gross mismanagement, willful misconduct, or gross
            negligence in the course of his/her employment with the Company; or
                (3) violated of any of the Company's policies, including, but
            not limited to, policies regarding sexual harassment, insider
            trading, confidentiality, substance abuse and/or conflicts of
            interest, which violation could result in the termination of the
            Participant's employment or removal as a director of the Company."
<PAGE>

  (8)  the current Section 1.20 ("LTPEP") is deleted in its entirety, and the
subsequent sections of the Plan are re-numbered sequentially;

  (9)  the current Section 1.22 ("Participant") is deleted in its entirety, and
replaced with the following text:

          "1.20  Participant - shall mean a person participating or eligible to
       participate in the Plan, as determined under Section 2.4."

  (10) the current Section 1.27 ("Pro-rated Bonus Award") is deleted in its
entirety, and replaced with the following text:

          "1.26  Pro-rated Bonus Award - shall mean an amount equal to the
       Incentive Award otherwise payable to a Participant for the Plan Year in
       which the Participant's termination of employment with the Company (other
       than for Ordinary Just Cause) is effective, multiplied by a fraction the
       numerator of which is the number of full and partial months in the
       applicable Plan Year through the date of termination of such
       Participant's employment, and the denominator of which is twelve (12)."

  (11) the current Section 1.28 ("Sun Stock") is deleted in its entirety, and
replaced with the following text:

       "1.27  Sunoco Stock - shall mean the common stock of Sunoco, Inc."

  (12) the current Article III ("Determination of Guideline Incentive
Awards") is deleted in its entirety, and replaced with the following text:

                                 "Article III
                  Determination of Guideline Incentive Awards

          3.1  Guideline Percentages.  Within the time prescribed by Section
       162(m) of the Code, the Committee will establish, in writing, the
       guideline incentive opportunities as a percentage of salary range
       midpoints for the applicable Plan Year. The salary range midpoint used in
       determination of the individual Guideline Incentive Award is the midpoint
       of the Participant's Hay point/grade under the salary administration
       program in effect on the last day of the final pay period of the current
       Plan Year.

          3.2  Guideline Incentive Award - The Guideline Incentive Award is
       calculated for each Participant by multiplying the individual Participant
       salary range midpoint by the applicable guideline percentage established
       by the Committee. Actual incentive awards to individual Participants may
       be greater or lesser than this guideline depending on Company and, as
       necessary, business unit, team and/or individual Participant
       performance."

  (13) the current Section 5.1 ("Forfeiture") is deleted in its entirety, and
replaced with the following text:

          "5.1  Forfeiture.   Provided that no Change in Control of the Company
       has occurred, if a Participant voluntarily terminates his or her
       employment with the Company (for any reason other retirement, death,
       permanent disability, approved leave of absence) prior to December 31 of
       any Plan Year, such Participant will not receive
<PAGE>

       payment of any Incentive Award for such Plan Year. Likewise, a
       Participant will not receive payment of any Incentive Award for a
       particular Plan Year if no Change in Control has occurred and the
       Participant's employment with the Company is terminated for Ordinary Just
       Cause before March 15 of the succeeding calendar year."

  (14) the following new Section 6.1(b) ("Negative Discretion") is added, and
the subsequent sections of the Plan are re-numbered sequentially:

               "(b)  Negative Discretion. The Committee will have the
          discretion, by Participant and by grant, to reduce (but not to
          increase) some or all of the amount of any Incentive Award that would
          otherwise be payable by reason of the satisfaction of the Performance
          Goals. In making any such determination, the Committee is authorized
          to take into account any such factor or factors it determines are
          appropriate, including but not limited to Company, business unit and
          individual performance; provided, however, the exercise of such
          negative discretion with respect to one executive may not be used to
          increase the amount of any award otherwise payable to another
          executive."

  (15) in the current Section 6.2(b) ("Deferral by Compensation Committee"), the
term "Compensation Committee" is deleted wherever it appears, and is replaced by
the term "Committee" in each instance.

  (16) the current Section 6.3 ("Awards of Sunoco Stock or Common Stock Units")
is deleted in its entirety, and replaced with the following text:

          "6.3  Awards of Sunoco Stock.  In the sole discretion of the
       Committee, all or a portion of each Participant's Incentive Award may be
       paid in shares of Sunoco Stock, all or a portion of which may be subject
       to certain restrictions for failure to meet applicable minimum stock
       ownership guidelines, or otherwise.
            (a) For a Participant subject to minimum stock ownership guidelines
          (as established from time to time by the Committee or the Company),
          but failing to meet the applicable personal ownership requirement
          within the prescribed period, the Committee may award shares of Sunoco
          Stock, from the treasury of the Company, subject to appropriate
          restrictions on sale, exchange, transfer, pledge, hypothecation, gift
          or other disposition.
            (b) The number of shares of Sunoco Stock to be issued from the
          Company's treasury pursuant to this Section 6.3 shall be determined by
          dividing:
                (1) the amount of the Incentive Award to be paid in Sunoco
            Stock; by
                (2) the average Fair Market Value of Sunoco Stock during the ten
            (10) consecutive trading days immediately preceding the date on
            which the Incentive award is to be paid.
            (c) All tax withholding will be satisfied from that remaining
          portion of the Incentive Award paid in cash."
<PAGE>

                     Sunoco, Inc. Executive Incentive Plan
                     Amendment Effective December 6, 2000
                     ------------------------------------

     Effective December 6, 2000, the Sunoco, Inc. Executive Incentive Plan (the
"Plan") is hereby amended as follows:

       (1) the current Article III ("Determination of Guideline Incentive
     Awards") is deleted in its entirety, and replaced with the following text:

                                  Article III
                  Determination of Guideline Incentive Awards

               3.1  Guideline Percentages. Within the time prescribed by Section
           162(m) of the Code, the Committee will establish, in writing, for the
           applicable Plan Year, the guideline incentive opportunities for
           Participants as a percentage of actual salary in effect on the last
           day of the final pay period of the current Plan Year.

               3.2  Guideline Incentive Award - The Guideline Incentive Award is
           calculated for each Participant by multiplying the individual
           Participant's actual salary in effect on the last day of the final
           pay period of the current Plan Year by the applicable guideline
           percentage established by the Committee.

           Actual incentive awards to individual Participants may be greater or
       lesser than this guideline depending on Company and, as necessary,
       business unit, team and/or individual Participant performance.