EXHIBIT 5.1

                 [STEWART MCKELVEY STIRLING SCALES LETTERHEAD]


File Reference: NS2112-85

June 21, 2002

MARATHON OIL CORPORATION
5555 San Felipe Road
Houston, TX 77056

MARATHON GLOBAL FUNDING COMPANY
c/o Marathon Oil Corporation
5555 San Felipe Road
Houston, TX 77056

Ladies and Gentlemen:

As set forth in the Registration Statement on Form S-3 (Registration Nos.
333-90034 and 333-90034-01), as amended (the "REGISTRATION STATEMENT"), filed
with the Securities and Exchange Commission (the "COMMISSION") by Marathon Oil
Corporation, a Delaware corporation ("MARATHON"), and Marathon Global Funding
Corporation, a Nova Scotia unlimited company ("MARATHON FUNDING"), under the
Securities Act of 1933, as amended (the "ACT"), relating to unsecured debt
securities of Marathon Funding (the "MARATHON FUNDING SECURITIES") fully and
unconditionally guaranteed by Marathon to be issued and sold by Marathon and
Marathon Funding from time to time pursuant to Rule 415 under the Act for an
aggregate initial offering price not to exceed U.S. $400,000,000, certain legal
matters in connection with the Securities are being passed upon for you by us.

In our capacity as your special Nova Scotia counsel in the connection referred
to above, we have examined (i) the Memorandum of Association and Articles of
Association of Marathon Funding (together, the "CHARTER DOCUMENTS"), (ii) the
Indenture dated as of June 14, 2002 among Marathon Funding, as issuer,
Marathon, as guarantor, and JPMorgan Chase Bank, as trustee (the "INDENTURE"),
pursuant to which the Marathon Funding Securities may be issued, and (iii) the
originals, or copies certified or otherwise identified, of corporate records of
Marathon Funding, certificates of public officials and of representatives of
Marathon Funding, statutes and other instruments and documents as a basis for
the opinions hereafter expressed.

Marathon Oil Corporation
June 21, 2002
Page 2

In expressing our opinion in paragraph 1 we have relied exclusively upon a
certificate of status pertaining to Marathon Funding issued on behalf of the
Registrar of Joint Stock Companies for the Province of Nova Scotia, dated June
13, 2002.

Based upon and subject to the foregoing, we are of the opinion that:

1.   Marathon Funding is an unlimited company duly incorporated and validly
     existing in good standing under the laws of the Province of Nova Scotia.

2.   Assuming that (i) the Indenture constitutes and enforceable obligation of
     Marathon Funding under the laws of the State of New York as provided
     therein, (ii) the Marathon Funding Securities have been duly executed,
     authenticated, issued and delivered in accordance with the provisions of
     the Indenture, and (iii) the choice of the laws of the State of New York
     to govern the Debt Securities is bona fide, the choice of the laws of the
     State of New York to govern the Debt Securities will be upheld as a valid
     choice of law and, if specifically pleaded and proved, the laws of the
     State of New York will be applied by the courts of competent jurisdiction
     in the Province of Nova Scotia, except with respect to procedure, which
     will be governed by the laws of Nova Scotia; provided that such choice of
     law is not contrary to public policy, as that term is understood under
     Nova Scotia law. Based solely on our review of the Indenture and our
     review otherwise described above but without having any knowledge of New
     York law we have no reason to believe that a court of competent
     jurisdiction in the Province of Nova Scotia would refuse to apply New York
     law to govern the Debt Securities.

The opinions set forth above are limited in all respects to matters of the laws
of the Province of Nova Scotia. We hereby consent to the filing of this opinion
of counsel as Exhibit 5.1 to Marathon's current report on Form 8-K reporting
the offering of the Marathon Funding Securities. In giving this consent, we do
not hereby admit that we are in the category of persons whose consent is
required under Section 7 of the Act or the rules and regulations of the
Commission thereunder.

Very truly yours,

STEWART MCKELVEY STIRLING SCALES

/s/ STEWART MCKELVEY STIRLING SCALES