According to the 1999 Mercury Grand Marquis Owner Guide :
( 5W-30 engine oil , certified for gasoline engines )
With engine oil filter change ( 4.7 litres / 5.0 U.S. quarts )
According to the 1999 Mercury Grand Marquis Owner Guide ( and one of Ford's websites ) ( Motorcraft FL-820-S , engine oil filter )
According to the 1997 Mercury Grand Marquis Owner Guide : ( 5W-30 ) is the PREFERRED oil
According to the 1996 Mercury Grand Marquis owners manual ( 5W-30 engine oil ) is the PREFERRED oil weight
( 5 quarts with filter change ) according to the 1999 Mercury Grand Marquis owners manual
According to the 1996 Mercury Grand Marquis Owner Guide : ( 5W-30 is the PREFERRED engine oil weight )
Bad Rings. Get your Rings replaced asap.
10-20 or 10-30 is a good weight
5w30
5 quarts ( 4.7 liters ) WITH ENGINE OIL FILTER CHANGE , according to the owners manual
A 1992 Mercury Grand Marquis came from the factory with ( 5W-30 )
According to the 1997 Mercury Grand Marquis Owner Guide : ( 5W-30 )
According to the 1996 Mercury Grand Marquis Owner Guide ( 5W-30 is the PREFERRED engine oil )