<Page>
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
FORM 8-K
CURRENT REPORT
Pursuant to Section 13 or 15(d)of the
Securities Exchange Act of 1934
Date of Report (date of earliest event reported): March 25, 2002
Commission File No. 1-14501
PENNZOIL-QUAKER STATE COMPANY
(EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)
DELAWARE 76-0200625
(State or other jurisdiction of (I.R.S. Employer
incorporation or organization) Identification No.)
Pennzoil Place
P.O. Box 2967
Houston, Texas 77252-2967
(Address of Principal Executive Offices)
Registrant's telephone number, including area code: (713) 546-4000
<Page>
ITEM 5. OTHER EVENTS
Pennzoil-Quaker State Company, a Delaware corporation (the "Company"),
has entered into an Agreement and Plan of merger dated as of March 25, 2002, by
and among Shell Oil Company, a Delaware corporation ("Shell"), Shell ND Company,
a Delaware corporation and a wholly owned subsidiary of Shell ("Merger Sub"),
and the Company (the "Merger Agreement"). The Board of Directors of the Company
has unanimously approved the Merger Agreement.
Under the terms of the Merger Agreement, each share of common stock of
the Company (the "Common Stock") will be converted into the right to receive $22
in cash, without interest.
The merger is conditioned upon, among other things, (i) approval of
the holders of the Common Stock, (ii) clearance under the Hart-Scott-Rodino
Antitrust Improvements Act of 1976 and (iii) other customary conditions. The
merger is expected to close in the second quarter of 2002.
In connection with the Merger Agreement, the Company has amended the
Rights Agreement dated as of December 18, 1998, between the Company and Mellon
Investor Services LLC (formerly The Chase Manhattan Bank), a national banking
association, as Rights Agent (the "Rights Agreement"). The Second Amendment to
Rights Agreement, dated as of March 25, 2002, to the Rights Agreement (the
"Second Amendment to Rights Agreement") exempts Shell, Merger Sub or any
affiliate or associate thereof and the execution and delivery of the Merger
Agreement and consummation of the transactions contemplated thereby from certain
provisions of the Rights Agreement.
On March 25, 2002, the Company and Shell issued a press release (the
"Press Release") regarding the execution of the Merger Agreement.
The foregoing description of the Merger Agreement does not purport to
be complete and is qualified in its entirety by reference to the Merger
Agreement, the Second Amendment to Rights Agreement and the Press Release, which
are filed as Exhibits hereto, and are incorporated herein by reference.
1
<Page>
ITEM 7. EXHIBITS.
Exhibit No. Description
2.1. Agreement and Plan of Merger dated as of March 25,
2002, by and among Shell Oil Company, Shell ND Company
and Pennzoil-Quaker State Company.
4.1. Second Amendment to Rights Agreement dated as of March
25, 2002, to the Rights Agreement between
Pennzoil-Quaker State Company and Mellon Investor
Services LLC (formerly The Chase Manhattan Bank), as
Rights Agent.
99.1. Press Release dated March 25, 2002.
2
<Page>
SIGNATURES
Pursuant to the requirements of the Securities Exchange Act of 1934,
the registrant has duly caused this report to be signed on its behalf by the
undersigned hereunto duly authorized.
Date: March 28, 2002 PENNZOIL-QUAKER STATE COMPANY
(Registrant)
By: /s/ PAUL B. SIEGEL
--------------------------
Name: Paul B. Siegel
Title: Senior Vice President
and General Counsel
3
<Page>
EXHIBIT INDEX
The following exhibits are filed herewith:
Exhibit No. Description
2.1. Agreement and Plan of Merger dated as of March 25,
2002, by and among Shell Oil Company, Shell ND
Company and Pennzoil-Quaker State Company.
4.1. Second Amendment to Rights Agreement dated as of
March 25, 2002, to the Rights Agreement between
Pennzoil-Quaker State Company and Mellon Investor
Services LLC (formerly The Chase Manhattan Bank), as
Rights Agent.
99.1 Press Release dated March 25, 2002.
4