EXHIBIT 10.58

                     FIRST AMENDMENT TO EMPLOYMENT AGREEMENT


H. Pete Smith (the  "Executive") and Ultramar Diamond  Shamrock  Corporation,  a
Delaware  corporation (the "Company")  hereby enter into this First Amendment to
the  Employment  Agreement  between the Executive  and the Company,  dated as of
November  25,  1996 and  effective  as of  December  3,  1996  (the  "Employment
Agreement").

WHEREAS, the Executive serves as Chief Financial Officer of the Company; and

WHEREAS,  the Executive and the Company entered into the Employment Agreement as
of the date stated above; and

WHEREAS,  Section  12.8  of the  Employment  Agreement  provides  that it may be
amended only by an instrument  in writing  approved by the Company and signed by
the Executive and the Company; and

WHEREAS,  to encourage the Executive to relocate from  Connecticut to Texas, the
Executive and the Company desire to amend the Employment  Agreement as described
below, and the Company has obtained all necessary approvals of such amendment.

NOW, THEREFORE,  in consideration of the promises and mutual covenants contained
herein and in the  Employment  Agreement,  it is agreed  that,  effective  as of
December  3, 1996  (being the  "Effective  Date," as  defined in the  Employment
Agreement),  a new  paragraph  is  added  to the end of  Section  5.5 (I) of the
Employment Agreement, to read as follows:

     "In addition,  if the Executive is involuntarily  terminated by the Company
     without Cause  (including for this purpose the termination by the Executive
     of his employment with Good Reason other than pursuant to clause (g) or (h)
     of Section  5.4 (I)),  or there  occurs a change in control  entitling  the
     Executive to an immediate  payout of his entire  benefit under the Ultramar
     Corporation  Supplemental  Executive Retirement Plan (the "Ultramar SERP"),
     the Company will pay to the Executive, within thirty days after such event,
     the excess, if any, of:

(a)  the lump sum  payment to which the  Executive  would be  entitled  upon the
     occurrence  of such  event  under the  Diamond  Shamrock  R&M  Supplemental
     Executive  Retirement  Plan (as in effect on the Effective Date, but taking
     into account any  subsequent  amendments  thereto which do not decrease the
     amount of benefits or the right to receive benefits) (the "Diamond Shamrock
     SERP") if the Executive had participated  therein  immediately prior to and
     at all times  following the Effective Date, but after  substituting  "fifty
     percent  (50%)"  for  "sixty  percent  (60%)"  in  Section 6 (a) (I) of the
     Diamond Shamrock SERP; over

     (b) the lump sum payment  actually made to the Executive under the Ultramar
         SERP;

     provided  that  if,  at the  time a lump  sum  payment  becomes  due to the
     Executive under the Ultramar SERP under the circumstances described in this
     paragraph,  a lump sum payment  would not  otherwise  be due the  Executive
     under the Diamond Shamrock SERP if he participated  therein.  In that event
     an actuarial firm which generally  performs  services for the Company shall
     translate the accrued Diamond Shamrock SERP benefit at such time (as if the
     Executive  participated  therein) into an actuarially  equivalent  lump sum
     benefit,  using  actuarial  assumptions  then applicable to the Executive's
     benefit under the Ultramar SERP."

IN WITNESS  WHEREOF,  the parties have executed this First Amendment on the date
indicated below, but effective as of the date described above.

AGREED:


/s/ H. PETE SMITH
    H. Pete Smith



ULTRAMAR DIAMOND SHAMROCK CORPORATION


By: /S/ ROGER R. HEMMINGHAUS
        Roger R. Hemminghaus
        Chief Executive Officer


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