Exhibit 10.38 FOURTH AMENDMENT TO THE PREMCOR RETIREMENT SAVINGS PLAN WHEREAS, The Premcor Refining Group Inc. ("Company") previously established the Premcor Retirement Savings Plan ("Plan"); and WHEREAS, the Company reserved the right to amend the Plan in Section 16.1 thereof; and WHEREAS, the Company desires to amend the Plan effective January 1, 2001; NOW, THEREFORE, effective January 1, 2001, the Plan is amended as follows: 1. Section 2.12 is amended by deleting the following phrase from the end of the first paragraph thereof: "and, if the Employer so elects for the look-back year, was in the top-paid group of Employees for such look-back year." 2. Section 4.1 is amended by deleting the last sentence thereof. IN WITNESS WHEREOF, the Company has caused this amendment to be executed by a duly authorized officer this 28th day of February, 2003. THE PREMCOR REFINING GROUP INC. By: /s/ James R. Voss ----------------- Name: James R. Voss Title: Senior Vice President