My reno stopped running. It'll turn over but won't fire. So I figured it was the fuel pump, so I went ahead and replaced that. Went to try and start it up but still nothing. Checked the spark plugs and #4 plug was covered in oil and could see oil in the cylinder. All the other cylinders and plugs are dry and normal. Could it be the piston rings? That's the first thing I thought, but I've heard valve cover gasket, valve stem tube, time chain, etc. so could you guys please help me out? Thanks!!

 

Have a compression test. Oil in the plugs could indicate worn out rings or seals.

 

It's true, you only need to do what was said by @eyeclose and the problems that you ask to be completed with ease.