USX <X> UNIT HIKES CRUDE OIL POSTED PRICES Marathon Petroleum Company, a subsidiary of USX Corp, said it lowered posted prices for crude oil by 50 cts with an effective date of October 16. The increase brings posted prices for West Texas Intermediate and West Texas Sour to 19.00 dlrs a barrel each. South Louisiana Sweet was increased to 19.35 dlrs a barrel. Several indepndent oil companies such as Permian Corp and Coastal Corp <CGP> said they had moved prices up effective last Friday the day Sun Co <SUN> announced a 50 cts a barrel increase to 19.00 dlrs a barrel.