Spark plug question

[Admiral Ballsy]

Originally Posted by suaveflooder

You think the plugs will last 100k?

Subaru apparently doesn't, since the spec is 60K.

My experience with long-term use of platinums has been mixed. I had one car go to ~95K with no issues, but three others needed new plugs in the ~50K-60K area. So the factory spec is probably reasonable.

[Bt216]

Hopefully someone will make a diy kn this

[retrosmiths]

Honest question. What happens if one of the 4 spark plugs went out? How will you feel/know it? An engine code? And what happens to the fuel that gets pumped there and not get burned?

-Sent from outer space

[Admiral Ballsy]

Originally Posted by retrosmiths

Honest question. What happens if one of the 4 spark plugs went out? How will you feel/know it? An engine code? And what happens to the fuel that gets pumped there and not get burned?

I've never had, nor heard of (in non-motorsports operation) a spark plug failure.

If one did, you'd definitely know it. You'd have tremendous vibration, lack of power, and CELs galore.

Spark plugs just wear out. Platinum, iridium, and other materials are used recently because they wear very very slowly - not because they're good conductors (which they aren't). Depending upon the design, though, they may not last as long as intended.

Some plugs use/used a little 'puck' of the material tack-welded to the cathode. AC/Delcos used to be made that way. And those little pucks tended to fall off, long before 100K, which didn't cause any failures, but resulted in incorrect gapping.


Regular old copper-conductor plugs are as good or better in terms of performance, all else equal. But they don't last anywhere near 100K, so automakers use platinum, et al so that they can 1) advertise really long tuneup intervals, and 2) design so that you can't change plugs without helluva work.

[hmong337]

I haven't even got my car yet and I'm already dreading the day I will have to swap them out