Exhibit 99.2


                       CERTIFICATION PURSUANT TO 18 U.S.C.
                      SECTION 1350, AS ADOPTED PURSUANT TO
                  SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002


In connection with the Annual Report of Valero Energy Corporation Thrift Plan on
Form 11-K for the year ended December 31, 2002, as filed with the Securities and
Exchange Commission on the date hereof (the Report), I, Donna M. Titzman, Member
of the  Administrative  Committee and  Treasurer of Valero  Energy  Corporation,
hereby  certify,  pursuant to 18 U.S.C.  Section  1350,  as adopted  pursuant to
Section 906 of the Sarbanes-Oxley Act of 2002, that:

|X|  The Report fully complies with the  requirements  of Section 13(a) or 15(d)
     of the Securities Exchange Act of 1934; and

|X|  The information  contained in the Report fairly  presents,  in all material
     respects,  the  financial  condition  and results of  operations  of Valero
     Energy Corporation Thrift Plan.

/s/ Donna M. Titzman
Donna M. Titzman
Member of the Administrative Committee and
Treasurer of Valero Energy Corporation
June 27, 2003


A signed  original  of the  written  statement  required by Section 906 has been
provided to Valero Energy Corporation Thrift Plan and will be retained by Valero
Energy  Corporation  Thrift Plan and  furnished to the  Securities  and Exchange
Commission or its staff upon request.