April 19, 2011

Tesoro Logistics LP
19100 Ridgewood Parkway
San Antonio, Texas 78259

Re:		Initial Public Offering of Common Units of Tesoro Logistics LP

Ladies and Gentlemen:

     We have acted as special counsel to Tesoro Logistics LP, a Delaware limited partnership (the “Partnership”), in connection with the proposed issuance of up to 14,950,000 common units representing limited partner interests in the Partnership (the “Common Units”). The Common Units are included in a registration statement on Form S-1 under the Securities Act of 1933, as amended (the “Act”), filed with the Securities and Exchange Commission (the “Commission”) on January 4, 2011 (Registration No. 333-171525) (such registration statement, as amended as of the effective date thereof, together with the registration statement filed by the Partnership on the date hereof pursuant to Rule 462(b) promulgated under the Act, being collectively referred to herein as the “Registration Statement”). This opinion is being furnished in connection with the requirements of Item 601(b)(5) of Regulation S-K under the Act, and no opinion is expressed herein as to any matter pertaining to the contents of the Registration Statement or related Prospectus, other than as expressly stated herein with respect to the issue of the Common Units.

     As such counsel, we have examined such matters of fact and questions of law as we have considered appropriate for purposes of this letter. With your consent, we have relied upon certificates and other assurances of officers of the general partner of the Partnership and others as to factual matters without having independently verified such factual matters. We are opining herein as to the Delaware Revised Uniform Limited Partnership Act (the “Delaware Act”) and we express no opinion with respect to any other laws.

     Subject to the foregoing and the other matters set forth herein, it is our opinion that, as of the date hereof, when the Common Units shall have been issued by the Partnership against payment therefor in the circumstances contemplated by the form of underwriting agreement most recently filed as an exhibit to the Registration Statement, the issue and sale of the Common Units will have been duly authorized by all necessary limited partnership action of the Partnership, and the Common Units will be validly issued, fully paid and nonassessable.

Tesoro Logistics LP
April 19, 2011
Page 2

     This opinion is for your benefit in connection with the Registration Statement and may be relied upon by you and by persons entitled to rely upon it pursuant to the applicable provisions of the Act. We consent to your filing this opinion as an exhibit to the Registration Statement and to the reference to our firm in the Prospectus under the heading “Validity of the Common Units.” 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 Act or the rules and regulations of the Commission thereunder.