AMENDMENT NO. 1 TO MASTER SUPPLY CONTRACT FOR RESALE OF OILS AND GREASES

Exhibit 10.38

AMENDMENT NO. 1

TO

MASTER SUPPLY CONTRACT

FOR

RESALE OF OILS AND GREASES

This AMENDMENT NO. 1 TO MASTER SUPPLY CONTRACT FOR RESALE OF OILS AND GREASES (this “Amendment No 1”) is made as of July 1, 2005 (the “Effective Date of Amendment No 1”), between ExxonMobil Oil Corporation (formerly known as Mobil Oil Corporation) (“Seller”) with offices at 3225 Gallows Road, Fairfax, VA 22037, and PETRO STOPPING CENTERS, L.P. (“Buyer”), with offices at 6080 Surety Drive, El Paso, TX 79905. (Seller and Buyer are sometimes referred to herein individually as a “Party” and collectively as the “Parties.”)

WHEREAS, Seller and Buyer have entered into that certain Master Supply Contract for Resale of Oils and Greases (the “Supply Contract”) dated as of July 23, 1999; and

WHEREAS, Seller and Buyer wish to amend certain terms, conditions, and provisions of the Supply Contract for the mutual benefit of the Parties;

NOW THEREFORE, the Parties agree as follows:

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(ii) Buyer agrees to purchase, or to use its commercially reasonable efforts to cause to be purchased at the Franchisee-Operated Truckstops, for the Truckstop Locations, the Minimum Purchase Gallons of Seller’s lubricants set forth in the table below for each remaining calendar year of the Initial Term, as adjusted from time to time pursuant to paragraphs (b), (c) and (d) below. The historical gallons requirements for the years 1999 through 2004 are shown for convenient reference. In the event that the Supply Contract is not extended into the Extended Term, the Minimum Purchase Gallons for the year 2009 shall be prorated, based on the actual number of days of Initial Term remaining in calendar year 2009. The Parties understand and agree that the Minimum Purchase Gallons for years after 2005 set forth below are based on an annual growth rate of one percent (1%) from the 2005 amount:

Minimum Purchase Gallons from PETRO Corp

Stores and PETRO Franchisee Stores

(iii) In the event that the Supply Contract is extended into the Extended Term, then (I) the Minimum Purchase Gallons for calendar year 2009 shall be 2,163,000, as indicated in the chart above (or as adjusted pursuant to paragraphs (b), (c) and/or (d) below), (II) the Minimum Purchase Gallons for calendar years 2010 through 2014 shall equal the Minimum Purchase Gallons for

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calendar year 2009, and (III) the Minimum Purchase Gallons for the year 2014 shall be prorated, based on the actual number of days of Initial Term remaining in calendar year 2014.

(iv) Buyer understands and agrees that except as set forth in the paragraph immediately below, and except for adjustments made pursuant to paragraphs (b), (c), and/or (d) below, the Minimum Purchase Gallons set forth in the table above, and in paragraph (iii) immediately above, are firm figures, and that if the total aggregate gallons required for the five (5) year period 2005 through 2009, (as these amounts may be adjusted in accordance with the terms and conditions of this Amendment No 1) are not purchased by Buyer and Buyer’s Franchisee-Operated Truckstops, then Buyer shall pay Seller, promptly after the end of such period, One Dollar ($1.00) for each gallon that such actual purchases for that period fall short of the aggregate required gallons for that period. In the event that the Supply Contract is extended into the Extended Term, and Buyer and the Franchisee-Operated Truckstops do not purchase the total aggregate gallons required for the five (5) year period of the Extended Term, then Buyer shall pay Seller, promptly after the end of such period, One Dollar ($1.00) for each gallon that Buyer’s actual purchases for that period fall short of the aggregate required gallons for that period.

(v) In the event that the price of bulk Delvac 1300 Engine Oil to Buyer from Seller for any consecutive sixty (60) day period in a calendar year is equal to or greater than the higher of (i) the price of Shell Rotella T plus ten (10) cents a gallon or (ii) the price of Chevron Delo plus ten (10) cents a gallon, then (i) the Minimum Purchase Gallons for that calendar year shall be reduced by one percent (1%), (ii) the remaining calendar years of the Initial Term shall be recalculated from such reduced base using a one percent (1%) growth rate, and (iii) if the Supply Contract is extended into the Extended Term, the remaining calendar years of the Extended Term shall also be recalculated accordingly, using a one percent (1%) growth rate.

(vi) In addition to the purchase requirements set forth above, Buyer shall purchase from Seller, in aggregate for Buyer-Operated Truckstops, ninety-five percent (95%) of all of its requirements of synthetic lubricants and ninety-five percent (95%) of all of its requirements of all lubricants other than diesel engine oils.

(vii) For purposes of this Supply Contract, 8 pounds of grease equals 1 gallon of conventional oil and 1 gallon of synthetic oil

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equals 4 gallons of conventional oil. As used in this Supply Contract, the terms “Seller’s product” and “Seller’s lubricants” are used interchangeably.