I have a 1997 Buick LeSabre, i juts bought it, don't know what type of motor oil to use. 5W or 10W, any difference? Also, is Synthetic motor oil any good?|||10w40 is what you want|||It should say in the owners manual, and on it oil cap, what oil should go into that engine.
5W30 is a thinner oil than 10W30, and is (theoretically) more energy conserving.|||Depends on what engine is in your car. If it is the 3.1L/3.4L then GM suggests 5w30, if you have the 3.8L then 10w30 is what it takes. Synthetic oil is always a welcome addition to any engine (except for a new or rebuilt because it doesn't allow proper "break in")