Swapped my plugs in my new to me 02 TJ 4.0 with 110k miles on it. If these werent the original plugs I would be surprised. They were Champions of some kind.
My .050(largest on my plug gapper) feeler gauge dropped right through. Center electrode is almost gone.
The jeep idles smooth, seems to have WAY more power. I just filled the tank so I will see what gas mileage is.
On another note, I think my valve cover gasket is leaking oil(by the evidence on plug 6 as well as the rest of the back of the motor). So what I thought was a RMS leak, may in fact be a valve cover gasket. I guess I will swap that out myself and hose the motor down with de-greaser and see what is leaking then. Also found a drivers front axle seal leak(oh what fun). And while I was under I found a small bracket on the clutch line that had not been attached to the bolt on the trans. Took the bolt out and it was covered in trans fluid(it smelled like gear oil and was slightly yellow compared to black motor oil). If anybody knows what bolt I am talking about(not the bottom most on drivers side, but one up from that), is it normal for it to be coated in gear oil? Or do I have yet another leaking seal of some kind(trans input shaft seal?)....