As a matter of fact i just changed mine out last weekend. The manual has it at 16000 miles.

When i pulled mine out they didn't look too bad at all. I figured if that's what the manual says then it's probably not a bad idea.

 

I went 35K. Replaced the air cleaner and plugs for the first time. The air cleaner looked terrible and the plugs while looking ok were all out of gap.

The above had a major change in performance. I should have changed
them way sooner. Will probably do both around 20k in the future.

 

Changed at 32300 and they still looked good. I will wait at least that long for the second set. Jim

 

30k

I went 50k on the first set and the gap had burned to make it much to wide. They plugs looked good, however. I will probably replace this set aet 25-30k.

 

Replaced mine at (I think it was 25,000) they were all slightly out gap and the front right one ( I do not know what cylnder #) was sort of dirty looking. Swapped them out for long summer trip. The engine was doing well.

 

The problem with spark plugs is they break down internally. You can't tell by looking at them, you need to put them on a plug tester. But as cheap as plugs are, just replace them if your performance goes down or when the manual specifies.

 

44

I'm at 18k on mine and i'm getting 44 mpg and she runs like a scalded dog.

 

i put new plugs in twice already !

110,000 smiles