GM-GMC: 96 S-10 2.2 runs rough, suspect gas in oil, exhaust sucks in, milky color, compression test

Question
Hi goodwrencher,

I have a 96 S10 with the 2.2 4 cylinder that is running rough. Someone told me it was a burnt/cracked valve because if you hold a dollar bill up to the tail pipe it sucks it up on a certain stroke and blows out on the rest as normal. To add to that, my oil pressure bottomed out so i pulled the stick only to see it was full. I drained some in a bottle and it was thin as water and smelled like gas. It didnt have a milky color that water would generally produce but the consistency was amazingly thin. I immediatly drained it and replaced along with a filter and regained oil pressure but i have no idea what the real cause is. I do know that plugs and wires are new and firing but i dont know exactly which cylinder is sucking through the exhaust or why. Any idea's?

Answer
You could start runnning the engine and then pulling a  plug to see which cylinder is misfiring. That plug will look different than the rest, maybe soaked with fuel or oil.  If you are getting fuel into your crankcase, it may be more likely that you have a fuel injector that is leaking or sticking open, causing that cylinder to misfire and wash the fuel down into the bottom end.  If you do locate the cylinder that is misfiring, do a compression test to see if it is a valve problem.  Do a wet compression test also (squirt some oil into the cylinder) if the cylinder is washed down with fuel, the rings may not seal and you may get a false compression test reading.
Hope this helps