1999 GMC Suburban Owner's Manual - Page 292

yellowblue Engine Oil (Gasoline Engine) If your vehicle has a diesel engine, see "Engine Oil (Diesel Engine)" in the Diesel Engine Supplement. It's a good idea to check your engine oil every time you get fuel. In order to get an accurate reading, the oil must be warm and the vehicle must be on level ground. The engine oil dipstick has a yellow ring handle and is located on the passenger's side of the engine. Turn off the engine and give the oil a few minutes to drain back into the oil pan. If you don't, the oil dipstick might not show the actual level. 6-12