What a recommended spark plug to be used in the rvr 4g63t

[milkandoj]

Oil could have gotten on the threads as you took them out. The tips look ok, not covered in carbon from being too cold or tuning problems and not white from too much heat either.

 

[bazeng]

Stock id go back to the recommended 6 heat range and see how they look after a service period. Might just be a case of too cold a plug for your application.

 

[umpc1611]

Oil could have gotten on the threads as you took them out. The tips look ok, not covered in carbon from being too cold or tuning problems and not white from too much heat either.

Well, I have the holes just about as clean as I can get them without removing the head, so if that's the case, it would indicate that there's oil coming from somewhere that shouldn't be there, right? As you noted from the condition of the tips, I really don't think it's unburned combustion chamber residue - although the exhaust does smell a bit rich, there's no real evidence on the plugs, and none from the running condition of the engine. Going to try this:

Stock id go back to the recommended 6 heat range and see how they look after a service period. Might just be a case of too cold a plug for your application.

After reading this thread, that's what I began to think. I don't know that it would have anything to do with the oil on the threads, but it's worth a try, so I'm going to try to find some NGK copper 6's (easier said than done, here) and run them for about 5k and report back. Thanks for the responses and suggestions, and keep 'em coming if you think of something else.