MPLX LP : 1Q 2021 Earnings Release Slides–May 4, 2021

First Quarter 2021

Earnings Conference Call

May 4, 2021

Forward‐Looking Statements

This presentation contains forward-looking statements within the meaning of federal securities laws regarding MPLX LP (MPLX). These forward-looking statements relate to, among other things, MPLX's expectations, estimates and projections concerning the business and operations, financial priorities and strategic plans of MPLX. You can identify forward-looking statements by words such as "anticipate," "believe," "commitment," "could," "design," "estimate," "expect," "forecast," "goal," "guidance," "imply," "intend," "may," "objective," "opportunity," "outlook," "plan," "policy," "position," "potential," "predict," "priority," "project," "proposition," "prospective," "pursue," "seek," "should," "strategy," "target," "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 the company's control and are difficult to predict. Factors that could cause MPLX's actual results to differ materially from those implied in the forward-looking statements include but are not limited to: the magnitude and duration of the COVID-19 pandemic and its effects, including travel restrictions, business and school closures, increased remote work, stay at home orders and other actions taken by individuals, government and the private sector to stem the spread of the virus, and the adverse impact thereof on our business, financial condition, results of operations and cash flows; the ability to reduce capital and operating expenses; the risk of further impairments; the amount and timing of future distributions; negative capital market conditions, including an increase of the current yield on common units; the ability to achieve strategic and financial objectives, including positive free cash flow in 2021, and with respect to distribution coverage, future distribution levels, proposed projects and completed transactions; the success of Marathon Petroleum Corporation's (MPC) portfolio optimization, including the ability to complete any divestitures on commercially reasonable terms and/or within the expected timeframe, and the effects of any such divestitures on the business, financial condition, results of operations and cash flows; adverse changes in laws including with respect to tax and regulatory matters; the adequacy of capital resources and liquidity, including, but not limited to, availability of sufficient cash flow to pay distributions and access to debt on commercially reasonable terms, and the ability to successfully execute business plans, growth strategies and self-funding models and to effect any common unit repurchases; the timing and extent of changes in commodity prices and demand for crude oil, refined products, feedstocks or other hydrocarbon-based products; continued/further volatility in and/or degradation of market and industry conditions as a result of the COVID-19 pandemic, other infectious disease outbreaks, natural hazards, extreme weather events or otherwise; general economic, political or regulatory developments, including changes in governmental policies relating to refined petroleum products, crude oil, natural gas or NGLs, or taxation; non-payment or non- performance by our producers and other customers; changes to the expected construction costs and timing of projects and planned investments, and the ability to obtain regulatory and other approvals with respect thereto; completion of midstream infrastructure by competitors; disruptions due to equipment interruption or failure, including electrical shortages and power grid failures; the suspension, reduction or termination of MPC's obligations under MPLX's commercial agreements; modifications to financial policies, capital budgets, and earnings and distributions; disruptions in credit markets or changes to credit ratings; compliance with federal and state environmental, economic, health and safety, energy and other policies and regulations and/or enforcement actions initiated thereunder; adverse results in litigation; other risk factors inherent to MPLX's industry; risks related to MPC; and the factors set forth under the heading "Risk Factors" in MPLX's Annual Report on Form 10-K for the year ended Dec. 31, 2020, and in Forms 10-Q and other filings, filed with Securities and Exchange Commission (SEC).

Factors that could cause MPC's actual results to differ materially from those implied in the forward-looking statements include but are not limited to: the magnitude and duration of the COVID-19 pandemic and its effects, including travel restrictions, business and school closures, increased remote work, stay at home orders and other actions taken by individuals, government and the private sector to stem the spread of the virus, and the adverse impact thereof on the business, financial condition, results of operations and cash flows; the ability to reduce capital and operating expenses; with respect to the planned sale of Speedway, the ability to successfully complete the sale within the expected timeframe, on the expected terms, or at all, based on numerous factors, including the failure to satisfy any of the conditions to the consummation of the planned transaction (including obtaining certain governmental or regulatory approvals on the proposed terms and schedule), the occurrence of any event, change or other circumstance that could give rise to the termination of the planned transaction; MPC's ability to utilize the proceeds as anticipated; the risk that the dissynergy costs, costs of restructuring transactions and other costs incurred in connection with the planned transaction will exceed our estimates; and our ability to capture value and realize the other expected benefits from the associated ongoing supply relationship following consummation of the planned sale; the risk that the cost savings and any other synergies from MPC's acquisitions may not be fully realized or may take longer to realize than expected; the risk of further impairments; the ability to complete any divestitures on commercially reasonable terms and/or within the expected timeframe, and the effects of any such divestitures on the business, financial condition, results of operations and cash flows; future levels of revenues, refining and marketing margins, operating costs, gasoline and distillate margins, merchandise margins, income from operations, net income and earnings per share; the regional, national and worldwide availability and pricing of refined products, crude oil, natural gas, NGLs and other feedstocks; consumer demand for refined products; disruptions in credit markets or changes to credit ratings; future levels of capital, environmental and maintenance expenditures; general and administrative and other expenses; the success or timing of completion of ongoing or anticipated capital or maintenance projects, including the conversion of MPC's Martinez Refinery to a renewable fuels facility; the receipt of relevant third party and/or regulatory approvals; the reliability of processing units and other equipment; the successful realization of business strategies, growth opportunities and expected investment; share repurchase authorizations, including the timing and amounts of such repurchases; the adequacy of capital resources and liquidity, including availability, timing and amounts of free cash flow necessary to execute business plans, complete announced capital projects and to effect any share repurchases or to maintain or increase the dividend; the effect of restructuring or reorganization of business components, including those undertaken in connection with the planned sale of Speedway; the potential effects of judicial or other proceedings, including remedial actions involving removal and reclamation obligations under environmental regulations, on the business, financial condition, results of operations and cash flows; continued or further volatility in and/or degradation of general economic, market, industry or business conditions as a result of the COVID-19 pandemic (including any related government policies and actions), other infectious disease outbreaks, natural hazards, extreme weather events or otherwise; general economic, political or regulatory developments, including changes in governmental policies relating to refined petroleum products, crude oil, natural gas or NGLs, or taxation; non-payment or non-performance by its producers and other customers; compliance with federal and state environmental, economic, health and safety, energy and other policies, permitting and regulations; the effects of actions of third parties such as competitors, activist investors or federal, foreign, state or local regulatory authorities or plaintiffs in litigation; the impact of adverse market conditions or other similar risks to those identified herein affecting MPLX; and the factors set forth under the heading "Risk Factors" in MPC's Annual Report on Form 10-K for the year ended Dec. 31, 2020, and in Forms 10-Q and other filings, filed with the SEC.

We have based our forward-looking statements on our current expectations, estimates and projections about our business and industry. We caution that these statements are not guarantees of future performance and you should not rely unduly on them, as they involve risks, uncertainties, and assumptions that we cannot predict. In addition, we have based many of these forward-looking statements on assumptions about future events that may prove to be inaccurate. While our management considers these assumptions to be reasonable, they are inherently subject to significant business, economic, competitive, regulatory and other risks, contingencies and uncertainties, most of which are difficult to predict and many of which are beyond our control. Accordingly, our actual results may differ materially from the future performance that we have expressed or forecast in our forward-looking statements. Any forward-looking statements speak only as of the date of the applicable communication and we undertake no obligation to update any forward-looking statements except to the extent required by applicable law. Copies of MPLX's Form 10-K, Forms 10-Q and other SEC filings are available on the SEC's website, MPLX's website at http://ir.mplx.com or by contacting MPLX's Investor Relations office. Copies of MPC's Form 10-K, Forms 10-Q and other SEC filings are available on the SEC's website, MPC's website at https://www.marathonpetroleum.com/Investors/ or by contacting MPC's Investor Relations office.

Non-GAAP Financial Measures

Adjusted EBITDA, distributable cash flow (DCF), distribution coverage ratio and leverage ratio, free cash flow (FCF) and excess/deficit cash flow are non-GAAP financial measures provided in this presentation. Adjusted EBITDA, DCF, FCF and excess/deficit cash flow reconciliations to the nearest GAAP financial measures are included in the Appendix to this presentation. Distribution coverage ratio is the ratio of DCF attributable to GP and LP unitholders to total GP and LP distributions declared. Leverage ratio is consolidated debt to last twelve months pro forma adjusted EBITDA. These non- GAAP financial measures are not defined by GAAP and should not be considered in isolation or as an alternative to net income attributable to MPLX, net cash provided by operating activities or other financial measures prepared in accordance with GAAP. Certain EBITDA forecasts were determined on an EBITDA-only basis. Accordingly, information related to the elements of net income, including tax and interest, are not available and, therefore, reconciliations of these forward-lookingnon-GAAP financial measures to the nearest GAAP financial measures have not been provided.

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Strategic Update

• Commitment to lowering cost structure and maintaining strict capital discipline
• Targeting excess cash after distributions and capital for 2021
• Remain committed to returning capital
• Expecting leverage to decline over time
• Advancing low carbon opportunities

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Commitment to ESG

Environment SocialGovernance

Targeting 50% methane emissions

intensity reduction by 2025

Received two EPA ENERGY STAR® Challenge for Industry Awards for

Energy Efficiency

Received API's Distinguished

Pipeline Safety Award

Human Rights Policy included in	Transparent reporting:
sustainability reporting
TCFD, SASB, GRI, CDP
Ongoing commitment to	Compensation includes 20%
Stakeholder Engagement and
Sustainability Metric
Community Investment
Safety and engagement	Diversity, Equity & Inclusion
prioritized through	linked to compensation

Earning Your Trust Program

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Logistics & Storage Segment

 Reduced operating expenses more than offset	1,000
872	24	896
lower revenues

• Pipeline throughputs averaged 5.1 MMBPD
• Terminal throughputs averaged 2.6 MMBPD
• Progressing Permian long-haul pipelines:
• • Wink to Webster crude oil
  • Whistler natural gas
  • NGL takeaway system

800

600

$MM

400

200

0

1Q20 L&S	1Q21 L&S
Adjusted EBITDA	Adjusted EBITDA

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