$3,000,000,000 AMENDMENT NO. 3 dated as of October 4, 2007 to the Five-Year Credit Agreement dated as of May 20, 2004 among

Exhibit 4.1

$3,000,000,000

AMENDMENT NO. 3

dated as of October 4, 2007

to the Five-Year Credit Agreement

dated as of May 20, 2004

among

Marathon Oil Corporation

The Co-Agents and Other Lenders Party Hereto

Bank of America, N.A.,
as Syndication Agent

Citibank, N.A. and

Morgan Stanley Bank,
as Documentation Agents,

and

JPMorgan Chase Bank, N.A.,
as Administrative Agent

AMENDMENT NO. 3 TO FIVE-YEAR CREDIT AGREEMENT

AMENDMENT dated as of October 4, 2007 to the Five-Year Credit Agreement dated as of May 20, 2004 (as heretofore amended, the “Credit Agreement”) among MARATHON OIL CORPORATION (the “Borrower”), the CO-AGENTS and other LENDERS (the “Lenders”) party hereto, BANK OF AMERICA, N.A., as Syndication Agent, CITIBANK, N.A. and MORGAN STANLEY BANK, as Documentation Agents and JPMORGAN CHASE BANK, N.A., as Administrative Agent (the “Administrative Agent”).

W I T N E S S E T H :

WHEREAS, Section 2.16 of the Credit Agreement contemplates that the Commitments under the Credit Agreement may be increased in the manner set forth therein, and the parties wish to memorialize an increase in the Commitments pursuant to this section;

WHEREAS, the parties wish to simultaneously amend Section 2.16(b) of the Credit Agreement as set forth herein to provide for additional increases in the Commitments which may be effected in that manner; and

WHEREAS, no Loans are currently outstanding under the Credit Agreement;

NOW, THEREFORE, the parties hereto agree as follows:

Section 1. Defined Terms; References. Unless otherwise specifically defined herein, each term used herein that is defined in the Credit Agreement has the meaning assigned to such term in the Credit Agreement. Each reference to “hereof”, “hereunder”, “herein” and “hereby” and each other similar reference and each reference to “this Agreement” and each other similar reference contained in the Credit Agreement shall, after this Amendment becomes effective, refer to the Credit Agreement as amended hereby.

Section 2. Amendment.

(a)           Section 2.16 is amended by inserting, following “Upon execution and delivery by the Borrower and such Lender or other financial institution of an instrument in form reasonably satisfactory to the Administrative Agent”, the language “and the delivery by the Borrower of evidence of appropriate corporate authorization on the part of the Borrower with respect to the increase in the aggregate amount of the Commitments as the Administrative Agent may reasonably request”.

(b)           Section 2.16(b) of the Credit Agreement is amended by changing the amount specified therein from $3,000,000,000 to $4,000,000,000.

Section 3. Changes in Commitments. With effect from and including the Amendment Effective Date, (i) the Commitment of each Lender shall be the amount set forth opposite the name of such Lender in the Commitment Schedule attached hereto and (ii) the Commitment Schedule attached hereto shall replace the Commitment Schedule attached to the Credit Agreement. On the Amendment Effective Date, the participations in all outstanding Letters of Credit shall be determined such that all Letters of Credit Liabilities are held by the Lenders in proportion to their respective Commitments.

Section 4. Representations of Borrower. The Borrower represents and warrants that (i) the representations and warranties of the Borrower set forth in Article 4 of the Credit Agreement will be true on and as of the Amendment Effective Date and (ii) no Event of Default will have occurred and be continuing on such date.

Section 5. Effect of Amendments. Except as expressly set forth herein, the amendments contained herein shall not constitute a waiver or amendment of any term or condition of the Credit Agreement, and all such terms and conditions shall remain in full force and effect and are hereby ratified and confirmed in all respects.

Section 6. Governing Law. This Amendment shall be governed by and construed in accordance with the laws of the State of New York.

Section 7. Counterparts. This Amendment may be signed in any number of counterparts, each of which shall be an original, with the same effect as if the signatures thereto and hereto were upon the same instrument.

Section 8. Effectiveness. This Amendment shall become effective as of the date hereof (the “Amendment Effective Date”), subject to satisfaction of the following conditions:

(a)           the Administrative Agent shall have received from the Borrower and from Lenders comprising the Required Lenders (which shall in any event include each Lender whose Commitment is increased pursuant to this Amendment) a counterpart hereof signed by such party or facsimile or other written confirmation (in form satisfactory to the Administrative Agent) that such party has signed a counterpart hereof; and

(b)           the Administrative Agent shall have received an opinion of the General Counsel or Assistant General Counsel of the Borrower dated

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as of the Amendment Effective Date, in form and substance satisfactory to the Administrative Agent.

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IN WITNESS WHEREOF, the parties hereto have caused this Amendment to be duly executed as of the date first above written.

COMMITMENT SCHEDULE