1

                                                                     EXHIBIT 8.1



                [OPINION OF SKADDEN, ARPS, SLATE, MEAGHER & FLOM]



                                                     February 11, 1999



Rutherford-Moran Oil Corporation
5 Greenway Plaza
Suite 220
Houston, Texas 77046

Ladies and Gentlemen:

                  We have acted as counsel to Rutherford-Moran Oil Corporation
("Rutherford-Moran"), a Delaware corporation, in connection with (i) the Merger,
as defined and described in the Agreement and Plan of Merger, dated as of
December 23, 1998 (the "Merger Agreement"), by and among Chevron Corporation, a
Delaware corporation, Merger Sub, a Delaware corporation and a wholly owned
subsidiary of Chevron, and Rutherford-Moran, and (ii) the preparation and filing
of the Registration Statement dated February 11, 1999 (the "Registration
Statement"), which includes the Proxy Statement/Prospectus (the "Proxy
Statement/Prospectus"), filed with the Securities and Exchange Commission (the
"Commission") under the Securities Act of 1933, as amended (the "Securities
Act"), and the Securities Ex-



   2

Rutherford-Moran Oil Corporation
February 11, 1999
Page 2



change Act of 1934, as amended. Unless otherwise indicated, each capitalized
term used herein has the meaning ascribed to it in the Merger Agreement.

                  In connection with this opinion, we have examined the Merger
Agreement, the Proxy Statement/Prospectus and such other documents as we have
deemed necessary or appropriate in order to enable us to render the opinion
below. For purposes of this opinion, we have assumed (i) the validity and
accuracy of the documents that we have examined and the facts concerning the
Merger that have come to our attention during our engagement and (ii) that the
Merger will be consummated in the manner described in the Merger Agreement and
the Proxy Statement/Prospectus.

                  Subject to the assumptions set forth above and the assumptions
and qualifications set forth in the discussion in the Proxy Statement/Prospectus
under the heading "Certain United States Federal Income Tax Consequences of the
Merger" ("the Discussion") and the fact that the Discussion is a summary and
does not purport to discuss all possible United States federal income tax
consequences of the Merger to Rutherford-Moran stockholders, we are of the
opinion that the Discussion states



   3

Rutherford-Moran Oil Corporation
February 11, 1999
Page 3



the material United States federal income tax consequences of the Merger to
Rutherford-Moran stockholders. We express no opinion as to whether the Discus-
sion addresses all of the United States federal income tax consequences of the
Merger. In addition, we express no opinion as to the United States federal,
state, local, foreign or other tax considerations, other than as set forth in
the Discussion. Further, there can be no assurances that the opinion expressed
herein will be accepted by the IRS or, if challenged, by a court. This opinion
is delivered in accordance with the requirements of Item 601(b)(8) of Regulation
S-K under the Securities Act.

                  In rendering our opinion, we have considered the applicable
provisions of the Code, Treasury Department regulations promulgated thereunder,
pertinent judicial authorities, interpretive rulings of the IRS and such other
authorities as we have considered relevant. It should be noted that statutes,
regulations, judicial decisions and administrative interpretations are subject
to change at any time (possibly with retroactive effect). A change in the
authorities or the accuracy or completeness of any of the information,
documents, corporate records, covenants, statements, representations or
assumptions on which our opinion is based could affect our conclusions. This
opinion is expressed as of the date hereof, and we are



   4

Rutherford-Moran Oil Corporation
February 11, 1999
Page 4


under no obligation to supplement or revise our opinion to reflect any changes
(including changes that have retroactive effect) (i) in applicable law or (ii)
if any information, document, corporate record, covenant, statement,
representation or assumption on which our opinion is based becomes untrue or
incorrect.

                  This letter is furnished to you solely for use in connection
with the Merger, as described in the Merger Agreement, and is not to be used,
circulated, quoted, or otherwise referred to for any other purpose without our
express written permission. In accordance with the requirements of Item
601(b)(23) of Regulation S-K under the Securities Act, we hereby consent to the
filing of this opinion as an exhibit to the Registration Statement " and to the
reference to our firm under the heading "Legal Matters" in the Proxy
Statement/Prospectus. In giving such consent, we do not thereby admit that we
are in the category of persons whose consent is required under Section 7 of the
Securities Act or the rules and regulations of the Commission thereunder.

                                        Very truly yours,

                                        /s/ SKADDEN, ARPS, SLATE, MEAGHER & FLOM