1993 Buick Riviera Owner's Manual - Page 227
1993 Buick Riviera Manual
Page 227 highlights
Add engine oil at the engine oil cap next to the oil fill dipstick. Just fill it enough to put the level somewhere in the proper operating range. Push the dipstick the way all back in when you're through. What Kind of Oil to Use: Look for three things: . sc "SG' must be on the oil container, either itself or by combined with other quality designations, such as "SG/CC," "SG/CD," "SF,SG,CC," etc. These letters show American Petroleum Institute (API) levels of quality. 225