CFI ? The fuel pressure regulator could be leaking.
You could have a cracked engine block.
If your 1990 Lumina has gas in the oil pan, then there could be a stuck injector flooding the engine. There can also be a blown head gasket. Driving the vehicle can destroy the engine.
Bottom of the engine mounted inside the oil pan on the engine block.
No you can not use gas engine oil in diesel engine oil because processing of diesel engine is different from gas engine oil. If you use this then it damage your vehicles.
A gas only engine has a spout where oil is added to the engine. If there is no spout, then it is a gas/oil engine. FYI - gas only engine is a four-stroke (four-cycle) engine and the gas/oil engine is two-stroke (two-cycle).
What grade of oil is best in your 5.3 liter Chevy engine?"
worn piston rings
that is a very hard question
Your engine has worn piston rings. Get it fixed asap because the oil is no good and will seize the motor. it can also come from flooding carb especially on new engine
4lts engine oil used
One of the valve covers.
For a 6.0L Chevy gas engine, it is generally recommended to use 5W-30 engine oil. This oil viscosity provides optimal performance across a range of temperatures. Always check the owner's manual for specific recommendations related to your vehicle's model year and driving conditions, as some may suggest different grades or types, including synthetic oil for improved performance and protection.