Maturity Extension Letter (Amendment No. 6) to Letter of Credit Agreement and Subsidiary Guaranty Agreement dated as of July 15, 2019 among NuStar Logistics, L.P., NuStar Energy L.P., the Lenders party thereto and MUFG Bank, Ltd., as Issuing Bank and Administrative Agent

Reference is made to (i) that certain Letter of Credit Agreement, dated as of September 3, 2014 (the “Original Agreement”), (ii) that certain Amendment No. 1 to Letter of Credit Agreement and Subsidiary Guaranty Agreement dated as of November 3, 2014 (the “Amendment No. 1”),(iii) that certain Maturity Date Extension Letter Amendment dated on or about August 18, 2015 (the “2015 Extension Letter”), (iv) that certain Maturity Date Extension Letter Amendment dated on or about July 15, 2016 (the “2016 Extension Letter”), (v) that certain Maturity Date Extension Letter Amendment dated July 13, 2017 (the “2017 Extension Letter”), and (vi) that certain Maturity Date Extension Letter Amendment dated July 12, 2018 (the “2018 Extension Letter”, and together with the Original Agreement, Amendment No. 1, the 2015 Extension Letter, the 2016 Extension Letter, the 2017 Extension Letter, and as further amended, restated, supplemented or otherwise modified from time to time, the “Agreement”) by and among NUSTAR LOGISTICS, L.P. and NUSTAR ENERGY L.P., both Delaware limited partnerships (together the “NuStar Parties”), the Lenders, and MUFG BANK, LTD., as Issuing Bank and Administrative Agent . Capitalized terms used but not defined herein shall have the respective meanings given to such terms in the Agreement.

Whereas the Agreement was intended to expire as of September 2, 2019, and whereas the Lenders, the NuStar Parties and the Administrative Agent mutually wish to extend the expiry of the Agreement until September 2, 2020, now therefore, for good and valuable consideration, the sufficiency of which is hereby acknowledged, the parties hereto agree as that the term “Maturity Date” as set forth in the Agreement is hereby amended to read “September 2, 2020” and Schedule 3.12 to the Agreement is hereby deleted in its entirety and replaced with Schedule 3.12 attached hereto.

The NuStar Parties hereby represent and warrant that (a) it has full power and authority, and has taken all action necessary, to execute and deliver this letter, (b) this letter has been duly executed and delivered by it and constitutes its legal, valid and binding obligation, enforceable in accordance with its terms, (c) after giving effect to the provisions of this letter, the representations and warranties of the NuStar Parties contained in Article III of the Agreement shall be true on and as of the date hereof as if they had been made on such date (except for those representations stated to be relate to a specific earlier date, which representations shall continue to be true and correct as of such earlier date), (d) no Default or Event of Default has occurred and is continuing on the date hereof, and (e) there have been no changes to the partnership agreements of the NuStar Parties since the date of the Agreement other than such amendments which have been furnished in compliance with Section 5.02(e) of the Agreement.

No other provision of the Agreement is amended by this letter. The NuStar Parties hereby confirm that the Agreement remains in full force and effect as amended hereby, and that all obligations of such NuStar parties set forth therein are ratified and reconfirmed. The execution, delivery and effectiveness of this letter shall not, except as expressly provided herein, operate as a waiver of any right, power or remedy of any Lender or the Agent under the Agreement or any of

the Loan Documents, nor constitute a waiver of any provision of the Agreement or any of the Loan Documents. This letter shall be construed in accordance with and governed by the law of the State of New York.

This letter may be executed by one or more of the parties to this letter on any number of separate counterparts (including by facsimile transmission or electronic transmission in portable document format of signature pages hereto), and all of said counterparts taken together shall be deemed to constitute one and the same instrument. Delivery of this letter by facsimile transmission or electronic transmission in portable document format shall be effective as delivery of a manually executed counterparty hereof.

Regards,