EXHIBIT 24.2
                               POWER OF ATTORNEY


     KNOW ALL MEN BY THESE PRESENTS, that the undersigned, on behalf of Ultramar
Diamond Shamrock Corporation, a Delaware corporation (the "Corporation"), hereby
constitutes and appoints Timothy J. Fretthold, H. Pete Smith, Curtis V.
Anastasio, and Todd Walker, attorneys-in-fact and agents of the Corporation,
with full power of substitution and resubstitution, to do any and all acts and
things in its name and on its behalf and to execute any and all instruments in
its name in such capacity which they may deem appropriate or advisable to enable
the Corporation to comply with the Securities Exchange Act of 1934, as amended,
and any rules and regulations of the Securities and Exchange Commission, in
connection with the Corporation's Annual Report on Form 10-K for the fiscal year
ended December 31, 1998, including without limitation, the power to sign such
report on the Corporation's behalf and to sign any amendments thereto, and to
file the same, with all exhibits thereto, and other documents required in
connection therewith, with the Securities and Exchange Commission, granting to
each and all of said attorneys-in-fact, full power and authority to do and
perform each and every act and thing requisite and necessary to be done in
connection with the filing of such report as herein described.

ULTRAMAR DIAMOND SHAMROCK CORPORATION


/s/ Jean Gaulin
- ----------------------
Jean Gaulin
Chief Executive Officer


Dated:  March 3, 1999