I took my car in for its 40,000 mile servicing today. I know that mountune recommends changing the plugs every 10,000 miles, and my tune has been on the car since about 10,000 miles, so 30,000 on the plugs. They all looked like I've been running a little rich, and one of the coils was just starting to go bad. I can only get 92 octane, not 93 so that may be a part of it. The car seem to be running a little better? The deterioration taking place over years so that it was not noticeable, but the mileage had been seeming to slip, which was why I decided to have the plugs looked at in the first place.
Anyway----moral of the story---- Check your plugs every 10,000! I know I'll be replacing mine now on a yearly basis.
Anyway----moral of the story---- Check your plugs every 10,000! I know I'll be replacing mine now on a yearly basis.