Tesoro Achieves Investment Grade Credit Rating with Standard & Poor's Upgrade

SAN ANTONIO, TEXAS - June 5, 2017 - Tesoro Corporation TSO announced today that S&P Global Ratings raised the Company's corporate credit and senior unsecured issue ratings to "BBB-" with a stable outlook from "BB+". S&P indicated "the stable outlook reflects our expectation that Tesoro will successfully integrate the Western Refining acquisition, continue to drive operational improvements and enhance margins at its refineries, while not meaningfully increasing consolidated financial leverage beyond current levels. We also believe the company will continue to manage the effects of carbon tax regulation on its business, expand and diversify its midstream business, and maintain ample liquidity."

In February 2017, Fitch Ratings assigned a first-time Long-Term Issuer Default Rating of BBB- to both Tesoro and TLLP, marking the companies' inaugural investment grade credit ratings.

As a result of Tesoro achieving a "BBB-" credit rating at both S&P and Fitch, the Company's outstanding unsecured bond securities now meet the criteria to be included in the investment grade Bloomberg Barclays Global Aggregate Index. Additionally, many of the provisions on Tesoro's $3.0 billion revolving credit facility will now become consistent with other investment grade credit facilities, providing the Company with incremental operational flexibility.

"This upgrade by S&P is further evidence of Tesoro's commitment to maintaining our financial strategy, including a strong balance sheet and credit metrics," said Steven Sterin, Executive Vice President and CFO. "Tesoro will continue to operate with financial discipline, enabling us to further invest in growth, return cash to shareholders in the form of share repurchases and dividends, and maintain a strong financial position."

About Tesoro Corporation
Tesoro Corporation, soon to become Andeavor, is an independent refiner and marketer of petroleum products. Tesoro, through its subsidiaries, operates 10 refineries in the western United States with a combined capacity of over 1.1 million barrels per day and ownership in a logistics business, which includes interest in Tesoro Logistics LP TLLP and Western Refining Logistics, LP WNRL and ownership of their general partners. Tesoro's retail-marketing system includes approximately 3,000 retail stations marketed under multiple well-known fuel brands, including ARCO®, SuperAmerica®, Shell®, Exxon®, Mobil®, Conoco®, Tesoro®, USA Gasoline(TM) and Giant®.

FORWARD LOOKING STATEMENTS
This release contains "forward-looking" statements within the meaning of Section 27A of the Securities Act of 1933 and Section 21E of the Securities Exchange Act of 1934, including without limitation statements concerning: our operational, financial and growth strategies, including continued growth, financial discipline, maintaining a strong balance sheet, financial position and credit metrics, operational improvements, enhancing refinery margins, managing the effects of carbon tax regulation, expanding and diversifying our midstream business, and returning cash to our shareholders; our ability to successfully effect those strategies and the expected timing and results thereof; our financial and operational outlook, and ability to fulfill that outlook; our financial position, liquidity and capital resources; the expected benefits of the investment grade credit rating; and the planned integration of Western Refining, and the expected benefits thereof. For more information concerning factors that could affect these statements, see our annual report on Form 10-K, quarterly reports on Form 10-Q, and other public filings and press releases, available at www.tsocorp.com. We undertake no obligation to revise or update any forward-looking statements as a result of new information, future events or otherwise.

Contacts:
Investors:
Brian Randecker, Investor Relations, (210) 626-4757

Media:
Tesoro Media Relations, media@tsocorp.com, (210) 626-7702