Exhibit 99.1

Marathon Petroleum Corporation Provides Interim

Second-Quarter 2013 Update

FINDLAY, Ohio, July 15, 2013 – Marathon Petroleum Corporation (NYSE: MPC) today announced that the company expects to report earnings in the range of $570 million to $600 million, or $1.75 to $1.85 per diluted share, for the second quarter of 2013, compared with earnings of $814 million, or $2.38 per diluted share, for the second quarter of 2012. Included in the second-quarter 2013 estimate are after-tax charges of approximately $39 million, or $0.12 per share, related to pension settlement expenses compared with approximately $53 million, or $0.15 per share, in the second quarter of 2012.

Second-quarter 2013 Refining and Marketing segment results are expected to be negatively impacted in comparison to second quarter of 2012 by a number of factors, such as lower crude oil price differentials and product realizations compared to spot market values, which MPC believes were impacted by the Renewable Fuels Standard.

The company will host a conference call on Aug. 1 at 10 a.m. EDT to provide an update on company operations and to discuss 2013 second-quarter financial results, which will be released earlier that day.

About Marathon Petroleum Corporation

MPC is the nation’s fourth-largest refiner, with a crude oil refining capacity of approximately 1.7 million barrels per calendar day in its seven-refinery system. Marathon brand gasoline is sold through approximately 5,000 independently owned retail outlets across 17 states. In addition, Speedway LLC, an MPC subsidiary, owns and operates the nation’s fourth-largest convenience store chain, with approximately 1,460 convenience stores in nine states. MPC also owns, leases or has ownership interests in approximately 8,300 miles of pipeline. Through subsidiaries, MPC owns the general partner of MPLX LP, a midstream master limited partnership. MPC’s fully integrated system provides operational flexibility to move crude oil, feedstocks and petroleum-related products efficiently through the company’s distribution network in the Midwest, Southeast and Gulf Coast regions. For additional information about the company, please visit our website at http://www.marathonpetroleum.com.

Investor Relations Contacts:

Pamela Beall (419) 429-5640

Beth Hunter (419) 421-2559

Media Contacts:

Angelia Graves (419) 421-2703

Jamal Kheiry (419) 421-3312

References to Earnings

References to earnings mean net income attributable to MPC from the statements of income. Unless otherwise indicated, references to earnings and earnings per share are MPC’s share after excluding amounts attributable to noncontrolling interests.

Forward-looking Statements

This press release contains forward-looking statements within the meaning of federal securities laws. These forward-looking statements relate to, among other things, MPC’s expectations, estimates and projections concerning MPC business and operations. You can identify forward-looking statements by words such as “anticipate,” “believe,” “estimate,” “expect,” “forecast,” “project,” “could,” “may,” “should,” “would,” “will” or other similar expressions that convey the uncertainty of future events or outcomes. Such forward-looking statements are not guarantees of future performance and are subject to risks, uncertainties and other factors, some of which are beyond MPC’s control and are difficult to predict. Factors that could cause actual results to differ materially from those in the forward-looking statements include: volatility in and/or degradation of market and industry conditions; the availability and pricing of crude oil and other feedstocks; slower growth in domestic and Canadian crude supply; completion of pipeline capacity to areas outside the U.S. Midwest; consumer demand for refined products; transportation logistics; the reliability of processing units and other equipment; our ability to successfully implement growth opportunities; impacts from our repurchases of shares of MPC common stock under our share repurchase authorization, including the timing and amounts of any common stock repurchases; state and federal environmental, economic, health and safety, energy and other policies and regulations; other risk factors inherent to our industry; the finalization of MPC’s financial statements for the quarter ended June 30, 2013; and the factors set forth under the heading “Risk Factors” in MPC’s Annual Report on Form 10-K for the year ended December 31, 2012 filed with the Securities and Exchange Commission (SEC). In addition, the forward-looking statements included herein could be affected by general domestic and international economic and political conditions. Unpredictable or unknown factors not discussed here or in MPC’s Form 10-K could also have material adverse effects on forward-looking statements. Copies of MPC’s Form 10-K are available on the SEC website, MPC’s website at http://ir.marathonpetroleum.com or by contacting MPC’s Investor Relations office.