Spark Plugs: The good the bad and the copper core

[rexer417]

Just replaced my spark plugs after 137k miles on my 05' WRX. Unfortunately I didn't plan ahead and had to settle for Autolite Platinums. They had NGK copper, but I'd rather have platinum.

Either way I am planning on switching them out after 5-10K I would like to try and replace them with something nice. Iridium seems to be the step up from plat.

There is double platinum, iridium, and whatever Pulstars are. Let me know what you think. I guess buying pre-gapped would be a good idea too.

On small side note, when I was replacing my plugs I checked the gap of my stock plugs and it was .040 for every single one. Is this just because the tip had worn down that much or did the factory not gap the plugs? I gapped my replacement plugs and all has been fine, has anyone else discovered this?

[WRX13oy]

ngk copper plugs actually give a better spark but at the cost of not lasting long. I use ngk plugs in my car and i switch them out every 8k miles (or 2 oil changes). I think the manual states that the gapping should be .028- .032 or something. i have mine gapped at .028 and have no problems what so ever. Also, since im changing the plugs more often, i get so see how the engine is running by looking at the condition of the plugs. but anyways, iridium plugs offer a long life

[dowright82]

Funny you mention that about your old plugs being gapped incorrectly . . .

I changed mine out at about 58k (just for the hell of it) with the one step colder NGK's (wish I could remember the part number, because I need to go buy some more soon)

I checked the gap of my stop plugs and they were all inconsistent and all of them OVER .35, one of them at .45!!

It was crazy how much better my car felt after the new coppers!! I highly recommend them!!

[pfsquirrel]

ngk copper plugs actually give a better spark but at the cost of not lasting long. I use ngk plugs in my car and i switch them out every 8k miles (or 2 oil changes). I think the manual states that the gapping should be .028- .032 or something. i have mine gapped at .028 and have no problems what so ever. Also, since im changing the plugs more often, i get so see how the engine is running by looking at the condition of the plugs. but anyways, iridium plugs offer a long life

8,000 miles?

You're buying new plugs that often? If so you're throwing your money down the drain. Plugs nowadays are minimum 60k+. If anything, check them every 10k or so for gap and fouling.

Everything I've read said copper gives a marginally better spark, but doesn't last quite as long. If you aren't running 100+ HP over stock, don't bother with the Cold +1's or more. The Stock Iridium should be the way to go, IMO. Stock WRX gap should be right around .030. I'm changing mine soon, and that's what I'm going with.