My car was having a bit of a rough time right after start up, as if trying to "catch it's breath" in a way. So, it had been a while since I changed plugs. I researched some, and the general thought was to stick to the stock AC Delco plats. I had Bosch Plat. +4 in there. Seemed to work pretty well. I removed them, and the valve cover gaskets are leaking some. Doesn't look like much, or very quickly, and I never notice any oil consumption. But the plugs sit in the V of the cams, and there was a little puddle in three of the four. The plugs didn't seem like they were all that tight. Didn't take much to get them out. Two of them, one awful, had oil that coated the threads. One seemed as though it made it to the cylinder. Two of the four plugs had just a slight ash build up, not much mind you. A different one, the electrode, I think.... it's the piece that comes through the center, was basically gone! It was still sparking, but probably not well. So I put the new Delcos in, and got them snug, and it runs great now.
Do you suppose oil made it down the plugs because they may have not been tight enough? (Or should that not have occurred regardless?)
Does the timing chain cover need to be removed to get the valve covers off?
I was thinking of replacing the gaskets, in the meantime, I put some high-temp sealant on it.
Tony