1995 GMC Sonoma Owner's Manual - Page 226

Engine Oil It's a good idea to check your engine oil every you get fuel. In order to time get an accurate reading, the oilmust be warm and thevehicle must be on level ground. 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. U To Check Engine Oil Pull outthe dipstick and clean it with a paper towel or cloth, push it then back in all the way. Remove it again, keeping the tip down.