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                                                                    EXHIBIT 3.13



                          CERTIFICATE OF INCORPORATION

                                       OF

                 PENNZOIL PRODUCTS INTERNATIONAL HOLDING COMPANY

                                   ----------

                                    ARTICLE I

      The name of the corporation is Pennzoil Products International Holding
Company.

                                   ARTICLE II

      The address of its registered office in the State of Delaware is
Corporation Trust Center, 1209 Orange Street, in the City of Wilmington, County
of New Castle. The name of its registered agent at such address is The
Corporation Trust Company.

                                   ARTICLE III

      The nature of the business or purposes to be conducted or promoted by the
corporation is to engage in any lawful business, act or activity for which
corporations may be organized under the General Corporation Law of Delaware.

                                   ARTICLE IV

      The total number of shares of stock which the corporation shall have
authority to issue is one thousand (1,000) shares of Common Stock, of the par
value of $1.00 per share (Common Stock). Each share of Common Stock shall
entitle the holder thereof to one vote at all meetings of the stockholders of
the corporation. Shares of such stock may be issued for such consideration and
for such corporate purposes as the Board of Directors may from time to time
determine.
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                                    ARTICLE V

      The name and mailing address of the incorporator signing the articles of
incorporation is:

                  Name                 Address
                  ----                 -------

                  Linda F. Condit      P.O. Box 2967
                                       Houston, Texas 77252-2967

                                   ARTICLE VI

      In furtherance of, and not in limitation of, the powers conferred by
statute, the Board of Directors is expressly authorized to make, alter or repeal
the by-laws of the corporation.

                                   ARTICLE VII

      No contract or other transaction between the corporation and any other
corporation and no other act of the corporation with relation to any other
corporation shall, in the absence of fraud, in any way be invalidated or
otherwise affected by the fact that any one or more of the directors of the
corporation are pecuniarily or otherwise interested in, or are directors or
officers of, such other corporation. Any director of the corporation
individually, or any firm or association of which any director may be a member,
may be a party to, or may be pecuniarily or otherwise interested in, any
contract or transaction of the corporation, provided that the fact that he
individually or as a member of such firm or association is such a party or so
interested shall be disclosed or shall have been known to the Board of Directors
or a majority of such members thereof as shall be present at any meeting of the
Board of Directors at which action upon any such contract or transaction shall
be taken any director of the corporation who is also a director or officer of
such other corporation or who is such a party or


                                       2
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so interested may be counted in determining the existence of a quorum at any
meeting of the Board of Directors which shall authorize any such contract or
transaction, and may vote thereat to authorize any such contract or transaction,
with like force and effect as if he were not such director or officer of such
other corporation or not so interested. Any director of the corporation may vote
upon any contract or other transaction between the corporation and any
subsidiary or affiliated corporation without regard to the fact that he is also
a director of such subsidiary or affiliated corporation.

                                  ARTICLE VIII

      The corporation shall have the right, subject to any express provisions or
restrictions contained in the certificate of incorporation or by-laws, from time
to time to amend the certificate of incorporation or any provisions thereof in
any manner now or hereafter provided by law, and all rights and powers at any
time conferred upon the directors or stockholders of the corporation by the
certificate of incorporation or any amendment thereof are subject to such right
of the corporation

      I, the undersigned, being the incorporator hereinbefore named, for the
purpose of forming a corporation pursuant to the General Corporation Law of the
State of Delaware, do make this certificate, hereby declaring that this is my
act and deed and that the facts herein stated are true and accordingly have
hereunto set my hand this 13th day of May, 1998.


                                        /s/ Linda F. Condit
                                        ----------------------------------------
                                                   Linda F. Condit


                                       3
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                           CERTIFICATE OF AMENDMENT OF

                          CERTIFICATE OF INCORPORATION

                                       OF

                 PENNZOIL PRODUCTS INTERNATIONAL HOLDING COMPANY

      Pennzoil Products International Holding Company, a corporation organized
and existing under and by virtue of the General Corporation Law of the State of
Delaware, does hereby certify:

      FIRST: That the Board of Directors of said Corporation, by unanimous
written consent, adopted a resolution proposing and declaring advisable the
following amendment to the Certificate of Incorporation of said Corporation:

            NOW, THEREFORE, BE IT RESOLVED, that the name of the Company be
      changed to Pennzoil-Quaker State Canada Holding Company and that ARTICLE I
      of the Certificate of Incorporation be amended to read as follows:

                                    ARTICLE I

            The name of the corporation is Pennzoil-Quaker State Canada Holding
            Company.

      SECOND: That in lieu of a meeting and vote of the stockholders, the
stockholder of the Corporation has given its unanimous written consent to said
amendment in accordance with the provisions of Section 228 of the General
Corporation Law of the State of Delaware.

      THIRD: That the aforesaid Amendment was duly adopted in accordance with
the applicable provisions of Sections 141,242 and 228 of the General Corporation
Law of the State of Delaware.

      IN WITNESS WHEREOF, said Pennzoil Products international Holding Company
has caused this Certificate to be signed by its President and attested by its
Assistant Secretary this 30th day of November, 1999.


                                        PENNZOIL PRODUCTS INTERNATIONAL
                                        HOLDING COMPANY

ATTEST:

  /s/ [ILLEGIBLE]                       By /s/ [ILLEGIBLE]
------------------------------------       -------------------------------------
        Assistant Secretary                              President