motorcraft 820 S
The 2006 Mercury Grand Marquis owners manual shows : The use of synthetic or synthetic blend motor oil is not mandatory - the oil just has to meet Ford specifications
( 5 quarts ) with engine oil filter change ( according to the 1996 Mercury Grand Marquis Owner Guide )
5w-30 is what I use in my 2000 grand marquis, in 2001 ford started saying 5w-20.
According to the 2002 Mercury Grand Marquis Owner Guide : With engine oil filter change : The 4.6 liter V8 engine takes ( 5.0 U.S. quarts of 5W-20 )
For a 2008 Mercury Grand Marquis, it's recommended to use 5W-20 motor oil, as specified in the owner’s manual. You can choose either conventional or synthetic oil based on your preference and driving conditions. Always check for oil that meets the API (American Petroleum Institute) certification standards for optimal performance.
According to the 2001 Mercury Grand Marquis Owner Guide ( 5W-20 ) ( with engine oil filter change , 5.0 U.S. quarts / 4.7 litres of 5W-20 engine oil )
According to the 1998 Mercury Grand Marquis Owner Guide : With engine oil filter change ( Motorcraft FL-820-S ) The 4.6 liter V8 engine takes ( 5.0 U.S. quarts / 4.7 litres of 5W-30 )
A 1999 Mercury Grand Marquis came from the factory with a 50 / 50 mix of distilled water and ( GREEN color antifreeze , meeting Ford specification ESE-M97B44-A )
According to the 2000 Mercury Grand Marquis Owner Guide ( 5W-30 ) ( with engine oil filter change , 5.0 U.S. quarts / 4.7 litres of 5W-30 engine oil )
5W-30
10-20 or 10-30 is a good weight