Marathon Oil Provides Fourth Quarter 2005 Interim Update

Marathon Oil Corporation provides information on market factors and operating conditions which occurred during the fourth quarter 2005 that could impact the company's quarterly financial results. The market indicators and company estimates noted below and in the attached schedule may differ significantly from the actual fourth quarter results. The company will report actual results on January 26, 2006. Details concerning the company's earnings conference call and webcast are noted at the end of this release.

Exploration and Production

Oil and natural gas production sold during the fourth quarter is estimated to be between 385,000 and 390,000 barrels of oil equivalent per day (boepd). Revenues are reported based on production sold during the period which can vary from production available for sale, primarily as a result of the timing of international crude oil liftings. Production available for sale during the fourth quarter is expected to be at the high end of the previous guidance of 350,000 to 370,000 boepd.

Sales volumes for the fourth quarter are up significantly compared to the third quarter primarily due to balancing the third quarter underlift position, seasonal gas sales and the restoration of Gulf of Mexico production.

As shown in the attached table, crude oil and natural gas market price indicators have remained strong during the fourth quarter. Marathon's actual crude oil and natural gas price realizations vary from these market indicators primarily due to product quality and location differentials.

Estimated fourth quarter exploration expense remains unchanged from previous guidance of between $60 and $80 million.

Refining, Marketing and Transportation

Market indicators for refining margins (crack spreads) in the Midwest and Gulf Coast were very strong during the fourth quarter of 2005. As a result of these very strong refining margins, favorable wholesale margins, widened sweet/sour differentials and continued solid operating performance during the fourth quarter, as described below, the company estimates its refining and wholesale marketing margin per gallon will be more than double that reported for the fourth quarter 2004.

Crude run rates remained strong during October and November averaging 961,000 barrels per day (bpd). The company estimates that crude runs for the quarter will average approximately 975,000 bpd.

The Speedway SuperAmerica LLC gasoline and distillate gross margin averaged approximately 15 cents per gallon in the first two months of the fourth quarter 2005, up substantially from both the fourth quarter 2004 and third quarter 2005. However, the fourth quarter 2005 retail gasoline and distillate margin is expected to be somewhat lower than 15 cents per gallon due to substantially lower retail margins in December.

Unallocated Administrative Expense

Total administrative expense for the quarter is expected to be approximately $70 to $85 million. This includes non-cash equity-based compensation expense estimated to be $10 to $15 million for the fourth quarter.

               Select Operating and Financial Data (unaudited)

                                        4Q         3Q      Oct.-Nov.     4Q
                                       2004       2005       2005       2005
                                      Actual     Actual     Actual     Actual
    Exploration and Production (E&P)
    Net Sales
      Domestic - Liquid
       Hydrocarbons (MBPD)              65.4       70.7       77.0       ---
      Domestic - Natural Gas
       (MMCFD)                         585.3      561.8      601.4       ---
      International - Liquid
       Hydrocarbons (MBPD)              96.9       86.3      150.2       ---
      International - Natural Gas
       (MMCFD)                         411.1      245.0      395.2       ---
        MBOED                          328.4      291.5      393.3       ---

    Marker Prices
      NYMEX prompt WTI oil price
       ($/BBL)                         48.27      63.31      60.35     60.05
      HH spot natural gas ($/MMBTU)     6.26       9.77      12.07     12.38
      HH bid Week natural gas price
       ($/MMBTU)                        7.07       8.53      13.89     13.00

    Average Sales Prices Excluding
    Liquid Hydrocarbons:
      Domestic ($/BBL)                 34.84      52.38      48.79       ---
      International ($/BBL)            38.72      48.24      48.48       ---
    Natural Gas
      Domestic ($/MCF)                  5.09       6.56       8.97       ---
      International ($/MCF)             3.79       3.12       5.64       ---

    Refining, Marketing and
    Chicago 6-3-2-1 crack spread
     ($/BBL)                            0.93      10.52      10.38      8.37
    Gulf 6-3-2-1 crack spread
     ($/BBL)                            0.14      11.06       8.44      7.10
    Chicago 3-2-1 crack spread
     ($/BBL)                            5.33      17.29      15.18     12.92
    Gulf 3-2-1 crack spread ($/BBL)     4.39      18.01      13.09     11.57

    *Sour Differential ($/BBL)        (11.15)     (9.52)    (11.68)   (12.17)
    Refinery Runs:
     Crude oil refined (MBPD)          974.7      979.6      960.5       ---
     Other charge & blend stocks
      (MBPD)                           200.4      215.2      264.8       ---
     Total (MBPD)                    1,175.1    1,194.8    1,225.3       ---
    Crude oil capacity
     utilization (%)                     103        103        100       ---
    Refined products sales volumes
     (MBPD)                          1,414.1    1,466.8    1,510.5       ---
    SSA gasoline and distillate
     sales (MMGal)                       793        825        556       ---
    SSA gasoline and distillates
     gross margin ($/gal)             0.1219     0.1232      .1531       ---
    SSA merchandise gross margin
     ($million)                          145        162        102       ---

     BBL - barrel
     MMBTU - million British Thermal Units
     MCF - thousand cubic feet
     MBPD - thousand barrels per day
     MBOED - thousand barrels of oil equivalent per day
     MMGal - millions of gallons
     MMCFD - million cubic feet per day

     * 15% Bow River, 15% Maya, 35% Kuwait, 35% Arab Medium