AMENDMENT TO INTERCREDITOR AGREEMENT

THIS AMENDMENT TO INTERCREDITOR AGREEMENT (this “ Amendment ”) is made as of June 16, 2009, by and among SOUTH TEXAS OIL COMPANY, a Nevada corporation (the “ Company ”), SOUTHERN TEXAS OIL COMPANY., a Texas corporation (“ Southern Texas ”), STO OPERATING COMPANY, a Texas corporation (“ STO Operating ”), STO PROPERTIES LLC, a Texas limited liability company (“ STO Properties ”), STO DRILLING COMPANY, a Texas corporation (“ STO Drilling ”; each of Company, Southern Texas, STO Operating, STO Properties, STO Drilling and each other Person (such term and each other capitalized term used but not defined herein shall have the meaning given to it in the Intercreditor Agreement described below) who guarantees, or grants a Lien on its assets to secure “Note Debt” and/or Convertible Debt is referred to individually as an “ Obligor ” and collectively as the “ Obligors ”), the Convertible Debt Creditors (as such term is amended hereby), the Buyers, and VIKING ASSET MANAGEMENT, LLC, a California limited liability company, in its capacity as collateral agent for itself and for the Buyers (including any successor agent, hereinafter, the “ Collateral Agent ”).

A.           The Company, The Longview Fund, L.P., a California limited partnership (“ Longview ”), and Longview Marquis Master Fund, L.P., a British Virgin Islands limited partnership (“ Marquis ”), entered into that certain Securities Purchase Agreement, dated as of April 1, 2008 (as amended, supplemented, restated or modified and in effect from time to time, the “ April Purchase Agreement ”), pursuant to which, among other things, (i) the Company issued to (a) Longview, among other things, senior secured notes in an aggregate original principal amount of $23,908,013.11 (such notes, together with any promissory notes or other securities issued in exchange or substitution therefor or replacement thereof, and as any of the same may be amended, supplemented, restated or otherwise modified and in effect from time to time, the “ Longview April Notes ”), and (b) Marquis, among other things, senior secured notes in an aggregate original principal amount of $8,469,337.71 (such notes, together with any promissory notes or other securities issued in exchange or substitution therefor or replacement thereof, and as any of the same may be amended, supplemented, restated or otherwise modified and in effect from time to time, the “ Marquis April Notes ”), and (ii) the Warrants (as defined therein) were amended and restated.

B.           Pursuant to that certain Securities Exchange Agreement dated as of February 20, 2009 between the Company and Longview and that certain Asset Purchase and Sale Agreement dated as of February 20, 2009 between the Company and Longview and certain of its affiliates, the Company issued to Longview approximately 1,600,000 shares of Series A Convertible Preferred Stock of the Company and sold certain assets of the Company to Longview in exchange for the surrender and cancellation of the Longview April Notes.

C.           The Company and each of the investors listed on the Schedule of Buyers attached thereto, including Marquis (the “ Initial Bridge Buyers ”) entered into a Securities Purchase Agreement, dated as of September 18, 2008 (as amended, restated, supplemented or otherwise modified and in effect from time to time, the “ Bridge Purchase Agreement ” and, together with the April Purchase Agreement, the “ Purchase Agreements ”), pursuant to which, among other things, subject to the terms and conditions set forth therein, the Company sold, and the Initial Bridge Buyers purchased, senior secured notes in the aggregate original principal amount of $7,000,000 (such notes, together with any promissory notes or other securities issued in exchange or substitution therefor or replacement thereof, and as any of the same may be amended, supplemented, restated or otherwise modified and in effect from time to time, the “ Initial Bridge Notes ”).

D.           Pursuant to that certain Assignment and Assumption Agreement, dated as of May 29, 2009, Marquis transferred to Summerview Marquis Fund, L.P. (“ Summerview ”; and together with Marquis as the holder of the Marquis April Notes and the Initial Bridge Buyers, the “ Buyers ”), among other things, a portion of the Marquis April Notes in the principal amount of $2,252,994.73 (the “ Summerview Transferred April Notes ”) and a portion of the Initial Bridge Notes in the principal amount of $1,759,556.47 (the “ Summerview Transferred Bridge Notes ”), with the remainder of the Marquis April Notes in the principal amount of $6,710,038.53 (the “ Marquis Remaining April Notes ”; and together with the Summerview Transferred April Notes and any promissory notes or other securities issued in exchange or substitution therefor or replacement thereof, and as any of the same may be amended, supplemented, restated or otherwise modified and in effect from time to time, the “ April Notes ”), and the remainder of the Initial Bridge Notes held by Marquis in the principal amount of $5,240,433.53 (the “ Marquis Remaining Bridge Notes ”; and together with the Summerview Transferred Bridge Notes, all other Initial Bridge Notes and any promissory notes or other securities issued in exchange or substitution therefor or replacement thereof, and as any of the same may be amended, supplemented, restated or otherwise modified and in effect from time to time, the “ Bridge Notes ”; the Bridge Notes and the April Notes, hereinafter, collectively the “ Notes ”) continuing to be held by Marquis.

E.           The Company entered into a Securities Purchase Agreement (as amended, restated, supplemented or otherwise modified and in effect from time to time as permitted hereunder, the “ First Convertible Debt Purchase Agreement ”), by and among the Company and certain investors party hereto as “First Convertible Debt Creditors” pursuant to which, among other things, subject to the terms and conditions set forth therein and in the Intercreditor Agreement (as defined below), the Company sold, and the First Convertible Debt Creditors purchased, secured convertible notes in the aggregate original principal amount of up to $480,000   (such notes, together with any promissory notes or other securities issued in addition to such notes pursuant to the First Convertible Debt Purchase Agreement or in exchange or substitution therefor or replacement thereof, and as any of the same may be amended, supplemented, restated or otherwise modified and in effect from time to time as permitted hereunder, the “ First Convertible Notes ”) and warrants to purchase shares of common stock of the Company.

F.           The Company desires to enter into a Securities Purchase Agreement (as amended, restated, supplemented or otherwise modified and in effect from time to time as permitted hereunder, the “ Second Convertible Debt Purchase Agreement ”; and collectively with the First Convertible Debt Purchase Agreement, the “ Convertible Debt Purchase Agreement ”), by and among the Company and certain investors party hereto as “Second Convertible Debt Creditors” pursuant to which, among other things, subject to the terms and conditions set forth therein and in the Intercreditor Agreement, the Company will sell, and the Second Convertible Debt Creditors will purchase, secured convertible notes in the aggregate original principal amount of up to $75,000   (such notes, together with any promissory notes or other securities issued in addition to such notes pursuant to the Second Convertible Debt Purchase Agreement or in exchange or substitution therefor or replacement thereof, and as any of the same may be amended, supplemented, restated or otherwise modified and in effect from time to time as permitted hereunder, the “ Second Convertible Notes ”; and together with the First Convertible Notes, the “ Convertible Notes ”) and warrants to purchase shares of common stock of the Company.

G.           The Convertible Debt Creditors, Obligors, Buyers and the Collateral Agent are parties to that certain Intercreditor Agreement dated as of June 10, 2009 (as amended, restated, supplemented or otherwise modified and in effect from time to time, the “ Intercreditor Agreement ”), pursuant to which the Convertible Debt Creditors agreed, among other things, that the Convertible Debt (as defined therein) is and shall be subordinated to the prior payment and performance in full of the Note Debt (as defined therein) upon the terms and subject to the conditions therein set forth.

H.           Concurrently herewith, Obligors and Buyers are entering into that certain June 2009 Waiver and Amendment Agreement dated as of the date hereof (the “ June 2009 Waiver ”), pursuant to which Marquis will agree to amend certain provision of the Notes and waive any and all violations or breaches of the Note Documents to the extent that any such violation or breach is the direct result of the Obligors’ issuance of the Second Convertible Notes.

I.           As a condition precedent to the effectiveness of the June 2009 Waiver, the Collateral Agent and Buyers have required the execution, delivery and performance of this Amendment by Obligors and Convertible Debt Creditors pursuant to which certain provisions of the Intercreditor Agreement shall be amended.

NOW, THEREFORE, in order to induce the Collateral Agent and Buyers to enter into and deliver the June 2009 Waiver, and to perform their respective obligations thereunder, and for other good and valuable consideration, the receipt and sufficiency of which hereby are acknowledged, the parties hereto agree as follows:

1.            Definitions .   All capitalized terms used but not elsewhere defined herein shall have the respective meanings ascribed to such terms in the Intercreditor Agreement.

2.            Amendments .

(a)           The recitals of the Intercreditor Agreement are hereby amended and restated in their entirety to read as follows:

A.           The Company, The Longview Fund, L.P., a California limited partnership (“ Longview ”), and Longview Marquis