Hi folks... how often do you think I should inspect/change my spark plugs? We have pisswater 95 RON (90 mon+ron/2) gas down here. I am running stock boost levels.

Any idea where I can purchase some 7 denso / NGK iridiums?

Hey,

I'm known to change my plugs fairly frequently. It was the first maintenance type thing I learned, and I spent a lot of time reading my plugs when running N20 on my Integra GSR.

I recently ordered NGK iridiums from SparkPlugs.com for my wife's WRX. Car runs great with them now, and I'll probably get the corresponding NGKs for my EVO.

Take care,

FB

Don't waste your time buying more; they're already in there. My Evo has NGK Iridiums as OEM plugs. I'd think they should last quite a long time.

I never changed my spark plugs on my Evo 8 yet but I think I'll change them after 10k miles.

even my USDM lancer had NGK iridiums in it

You shouldn't have to change your plugs until after a long time, about 10-20K miles.
__NiTe__

Whatup,

Sorry fellas, I meant that I will buy more at 15K miles or so in my EVO (currently only at 4k) to replace the ones that are in there. I didn't mean to go out and buy NGK iridiums and install them.

I think the iridiums are the way to go, and should last well, but I'll prob change at 12-15K miles even if they should last 30K or whatever. In the past I used coppers and changed them more frequently, but I think I'll stick with iridium for my EVO (and my WRX).

Take care,

FB

I heard that Iridiums have a "theoretical" life of 40,000km, and that Platinums had a theoretical life of 80,000km.

Is this true? I have had HKS Iridiums in there for 30,000km, and it still looks pretty good. Very minor wear on the top electrode. No misfires, and idling still seems okay. (I could never call it good, not even when it was new!)

I don't know what the theoretical life of iridium plugs are, but I'm DEFINITELY not changing mine at 15k. Waste of money! These plugs should be good AT LEAST until 40k. These aren't quick dying copper plugs!

You don't need to change spark plugs often. I think it's just a waste of money. Those iridiums plugs is not cheap too.

I will recommended for every 10k miles, removed the spark plugs and check the condition. Iridiums is a hard metal, so it won't wear out easily. If you see wear out, replace it. At most time, you might find carbon buildup around the spark plug. Clean up the carbon, your spark plug will performed as new.

Also check the gap of the spark plug. Proper gap will give your car the most performance.