EXHIBIT 5.1

                        [Letterhead of Thompson Hine LLP]


May 20, 2004

The Lubrizol Corporation
29400 Lakeland Boulevard
Wickliffe, Ohio 44092-2298


      Re:  Registration Statement on Form S-3

Ladies and Gentlemen:

      The Lubrizol Corporation (the "Company") is filing with the Securities and
Exchange Commission on or about the date hereof a Registration Statement on Form
S-3 (the "Registration Statement") relating to the offering from time to time,
pursuant to Rule 415 promulgated under the Securities Act of 1933, as amended
(the "Securities Act"), by the Company of the following securities with an
aggregate offering price of up to $2.0 billion: (i) certain debt securities (the
"Debt Securities") and (ii) Common Shares, without par value (the "Common
Shares"), including Common Shares that may be issued upon conversion of the Debt
Securities. The offering of the Debt Securities and the Common Shares will be as
set forth in the prospectus contained in the Registration Statement, as
supplemented by one or more supplements to such prospectus (the "Prospectus").

      Item 601 of Regulation S-K requires that an opinion of counsel concerning
the legality of the securities to be registered be filed as an exhibit to the
Registration Statement. This opinion is provided in satisfaction of that
requirement.

      In rendering this opinion, we have examined the originals, or copies
identified to our satisfaction, of such corporate records of the Company,
certificates of public officials, officers of the Company and other persons, and
such other documents, agreements and instruments as we have deemed relevant and
necessary for the basis of our opinions hereinafter expressed. In such
examination, we have assumed the following: (a) the authenticity of original
documents and the genuineness of all signatures; (b) the conformity to the
originals of all documents submitted to us as copies; and (c) the truth,
accuracy and completeness of the information, representations and warranties
contained in the records, documents, instruments and certificates we have
reviewed.

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

      1. The Debt Securities will be valid and legally binding obligations of
the Company at such time as: (a) the terms of the Debt Securities and of their
issuance and sale have been duly authorized by all necessary actions of the
Company, and have been established so as not to violate any applicable law; (b)
the Debt Securities have been duly executed, authenticated and delivered in
accordance with the applicable indenture or supplemental indenture; (c) the
Registration Statement has become effective; (d) an indenture relating to the
Debt Securities has been duly qualified under the Trust Indenture Act of 1939,
as amended (the "TIA"); and (e) the Debt Securities have been duly issued and
sold as contemplated by the Registration Statement, the Prospectus and the
indentures or any applicable supplemental indentures that have been qualified
under the TIA.



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      2. The Common Shares will be validly issued, fully paid and nonassessable
at such time as: (a) the terms of the issuance and sale of the Common Shares
have been duly authorized by all necessary actions of the Company; (b) the
Common Shares have been duly issued and sold as contemplated by the Registration
Statement and the Prospectus; and (c) the Company has received the consideration
for the Common Shares as approved by the Board.

      The information set forth herein is as of the date hereof. We assume no
obligation to advise you of changes that may hereafter be brought to our
attention. Our opinion is based on statutory laws and judicial decisions that
are in effect on the date hereof, and we do not opine with respect to any law,
regulation, rule or governmental policy that may be enacted or adopted after the
date hereof, nor do we assume any responsibility to advise you of future changes
in our opinion.

      Our opinion is intended solely for the benefit of the Company, and may not
be relied upon for any other purpose or by any other person or entity or made
available to any other person or entity without our prior written consent,
except that we hereby consent to the use and filing of this opinion as an
exhibit to the Registration Statement as filed with the Securities and Exchange
Commission and to the reference to us under the heading "Legal Matters" in the
Prospectus and the Registration Statement.

Very truly yours,

/s/ Thompson Hine LLP

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