Assuming this vehicle is fuel injected, you can do a leak down test.
Someone is putting it there. There is no way for oil to get from the engine to your fuel tank by natural means. Literally, if you have oil in your fuel tank, someone is sabotaging your vehicle by putting the oil there.
Getting rid of an old oil tank is a difficult task. The oil will have to removed first. You may be able to donate the oil. The tank must them be cut in half in order to get it out of the house. Call your local trash collection company to find out where you can take the tank for disposal.
The best solution to your problem is an in-frame overhaul. If fuel is getting into your oil, or oil into your fuel, you've got worn piston rings.
Leaky fuel injector(s).
Coolant getting into the fuel or oil.
At the very least, to fuel your Hummer.
If air or fluid was getting into the oil passages. Is the oil looking "bubbly" or "milkshake" like? Then coolant is getting into the oil, either by head gasket or somewhere else. If it smells gassy then fuel is getting into the oil.
Oil. It is becoming more difficult to find and produce oil. The oil boom is over.
if you have a mechanical fuel pump on the side of your block, the diaphragm has a hole in it which will dump fuel straight into your oil. a low cost fix.
needs a new fuel pump
Dry cylinder has 2 definition 1 no fuel is getting to the cylinder 2 no oil getting to it
If you're getting gasoline in the oil, then you have bad piston rings that are allowing gases into the crankcase. You can find which piston(s) have bad rings by doing a compression test; a cylinder with bad rings will have lower compression.