I have a 97 SS M6 with a 355 cam heads and all the bolt ons the motor only has about 10k-12k miles and i keep having #8 plug with oil on it and sometimes it backs out the car also has a bad shake or it could be a miss i dont know because i dont keep it in 6th to long because its that bad, it also has a stumble through all the gears but sixth is the worst also the heads have the same miles and were done by TEA someone please help

 

I had oil on #8 with only 25K on the motor. I installed new valve stem seals
when I changed the valve springs. I noticed that the #8 valve stem seal
was a tad loose and in the worse condition of all the seals. Here is a pick of
the plug. I don't use +4s any more and only have 3K on the NGK TR5s.

Fugly Plug

 

Does that mean the plug is coming out ?

Are you getting a SES light for misfires?????????

Is the oil internal on the electrode of the plug or external on the outside of the plug???????

Have you checked to see if that cylinder is dead???????

 

Maybe too simple but check to see that the intake is tight, the intake loosening up and causing internal and external oil leaks is a known problem.

 

Also consider replacing the plug wire. Or maybe use it on another cylinder and see if the fouling goes with it. If it smokes when you start it, then it's the valve seal. Good luck