The oil capacity for a 1991 Buick Century 3.3 is approximately 5 quarts. The recommended oil type is 10 W 30.
The Buick needs 5qts of SAE 5W-30.
SHOULD BE 5 QUATS
4.5 quarts of 5W-30
i have a 1996 buick century just came back from mechanic head gasket is gone and there is anti freeze in my oil i guess if you had water in your rad then you would have water in your oil.
Right under the power steering pump.
Usually 4.5 quarts to 5 quarts
always look in your owners manual. but I've driven and maintained a 90 91 93 buick century. if 6 cylinder i would suggest 4.4 litres or oil and change the oil filter at every oil change.