My car is a 1995 Intrepid ES 3.5l. It's been running pretty well since I got it, but it has recently been having some major issues (overheating, mostly). I haven't found any major coolant leaks on the outside, so I went to check the spark plugs to see if any coolant is getting into the cylinders, and I found oil on #1. And when I say I found oil, I mean the spark plug was covered in oil. Has anyone else here had this issue, and what could be causing this?