First Quarter 2014 Earnings Conference Call and Webcast

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May 1, 2014

MPLX Forward‐Looking Statements

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This presentation contains forward-looking statements within the meaning of the federal securities laws. These forward-looking statements relate to, among other things, MPLX's expectations, estimates and projections concerning the business and operations of MPLX and Marathon Petroleum Corporation (“MPC”). 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 the issuer’s control and are difficult to predict. Factors that could cause MPLX actual results to differ materially from those in the forward-looking statements include: the adequacy of our capital resources and liquidity, including, but not limited to, availability of sufficient cash flow to pay distributions and execute our business plan; the timing and extent of changes in commodity prices and demand for crude oil, refined products, feedstocks or other hydrocarbon-based products; volatility in and/or degradation of market and industry conditions; completion of pipeline capacity by our 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 our commercial agreements; our ability to successfully implement our growth strategy, whether through organic growth or acquisitions; state and federal environmental, economic, health and safety, energy and other policies and regulations; other risk factors inherent to our industry; and the factors set forth under the heading "Risk Factors" in MPLX's Annual Report on Form 10-K for the year ended December 31, 2013, filed with the Securities and Exchange Commission (the “SEC”). Copies of MPLX's Form 10-K are available on the SEC website, MPLX’s website at http://ir.mplx.com or by contacting MPLX's Investor Relations Office. Factors that could cause MPC’s actual results to differ materially from those in the forward-looking statements include MPC’s ability to successfully implement growth opportunities 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, 2013, filed with the SEC. 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. In addition, unpredictable or unknown factors not discussed here or in MPC’s Form 10-K or MPLX's Form 10-K could also have material adverse effects on forward-looking statements.

Other Information Adjusted EBITDA and distributable cash flow are non-GAAP financial measures provided in this presentation. Adjusted EBITDA and distributable cash flow reconciliations to the nearest GAAP financial measure are included in the Appendix to this presentation. Adjusted EBITDA and distributable cash flow are not defined by GAAP and should not be considered in isolation or as an alternative to net income attributable to MPLX or other financial measures prepared in accordance with GAAP.

Highlights Increased distribution to $0.3275 per unit – a 4.8 percent over fourth-

quarter 2013 and 20.2 percent over first-quarter 2013

Reported $37.7 million of distributable cash flow and adjusted EBITDA of $43.8 million

Acquired additional 13% interest in MPLX Pipe Line Holding LP

Continued to progress Cornerstone pipeline project

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Net Income 1Q 2014 vs. 1Q 2013 Variance Analysis

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35.3

16.6

7.1 (2.0) 0.9 1.7 (2.4) (1.5) 55.7 (21.5)

34.2

0

10

20

30

40

50

60

70

1Q 2013(100% Basis)

DeferredRevenue

Tariffs Volumes OtherRevenue

and Income

Cost ofRevenues

and RelatedParty

Purchases

G&A Other 1Q 2014(100% Basis)

MPCRetainedInterest

1Q 2014Attributable

to MPLX

$MM

MPLX Adjusted EBITDA and Distributable Cash Flow

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($MM) 1Q 2014 1Q 2013

Adjusted EBITDA 69.3 47.4

Less: Adjusted EBITDA attributable to MPC-retained interest 25.5 22.3

Adjusted EBITDA attributable to MPLX LP 43.8 25.1

Plus: Current period deferred revenue for committed volume deficiencies 7.7 4.7

Less: Cash interest paid, net 0.4 0.2

Maintenance capital expenditures paid 1.9 1.5

Volume deficiency credits 11.5 0.1

Distributable cash flow attributable to MPLX LP 37.7 28.0

Distribution declared

Limited partners – public 6.5 5.4

Limited partner – MPC 17.7 14.7

General partner – MPC 0.5 0.4

Incentive distribution rights – MPC 0.3 -

Total distribution declared 25.0 20.5

Coverage ratio 1.51x 1.37x

Financial Performance

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18.2 25.1 26.7

30.5 28.9

43.8

-5

5

15

25

35

45

4Q12 1Q13 2Q13 3Q13 4Q13 1Q14

$MM

Adjusted EBITDA*

16.7

28.0 27.2 31.1

28.3

37.7

0

10

20

30

40

4Q12 1Q13 2Q13 3Q13 4Q13 1Q14

$MM

Distributable Cash Flow*

Note: 4Q12 is for 2 months, 10/31/2012 to 12/31/2012 *Attributable to MPLX

MPLX Strong Financial Flexibility to Manage and Grow Asset Base

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($MM except ratio data) As of 3/31/14

Cash and cash equivalents 40.6

Total assets 1,193.7

Long-term debt* 280.4

Total equity 821.1

Consolidated total debt to consolidated EBITDA ratio (covenant basis)** 2.2x

*Includes amounts due within one year **Maximum covenant ratio <= 5.0 or 5.5 during the six month period following certain acquisitions

Distribution Growth per Unit

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0.2625*

(MQD) 0.2725

0.2850 0.2975

0.3125 0.3275

0.20

0.22

0.24

0.26

0.28

0.30

0.32

4Q12 1Q13 2Q13 3Q13 4Q13 1Q14

$/U

nit

1.51x

*Represents minimum quarter distribution (MQD) for 4Q12, actual $0.1769 equal to MQD prorated

Coverage Ratio 1.37x 1.25x 1.27x 1.38x 1.19x

IPO 10/31/2012

1st drop 5/1/2013 $100 MM

2nd drop 3/1/2014 $310 MM

Appendix

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MPLX LP Adjusted EBITDA and Distributable Cash Flow Reconciliation from Net Income

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($MM) 1Q 2014 1Q 2013

Net income 55.7 35.3

Less: Net income attributable to MPC-retained interest 21.5 17.7

Net income attributable to MPLX LP 34.2 17.6

Plus: Net income attributable to MPC-retained interest 21.5 17.7

Depreciation 12.6 11.7

Non-cash equity-based compensation 0.4 0.2

Net interest and other financial costs 0.6 0.2

Adjusted EBITDA 69.3 47.4

Less: Adjusted EBITDA attributable to MPC-retained interest 25.5 22.3

Adjusted EBITDA attributable to MPLX LP 43.8 25.1

Plus: Current period deferred revenue for committed volume deficiencies 7.7 4.7

Less: Cash interest paid, net 0.4 0.2

Maintenance capital expenditures paid 1.9 1.5

Volume deficiency credits 11.5 0.1

Distributable cash flow attributable to MPLX LP 37.7 28.0

MPLX Deficiency Payment Effect Example for illustrative purposes only

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($MM)

Quarter 1

Quarter 2

Quarter 3

Quarter 4

Quarter 5

Quarter 6

Quarter 7

Quarterly deficiency payment 2 5 3 5 - - -

Use or expiration of credit (on or before) - - - - 2 5 3

Cumulative deferred revenue 2 7 10 15 13 8 5

Distributable cash flow Yes Yes Yes Yes No No No

Adjusted EBITDA No No No No Yes Yes Yes

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