hey, i came accross this a while ago and i think its quite useful... someone else might find it useful aswell so here goes
How to read your Spark plugs Car & Motorbikes
good stuff rep point added for helpfull thread.
* RVN 355 *
oh good, my V6 plugs seem to just be telling me my motor is old. Burning oil, oil running into cylinder, running rich. I have a wonderful array of plugs that seem to tell me more than that though... All sorts of signs that I don't know what they mean. They have been in the car for 2 years though... if they weren't Iridiums they'd have been long gone I assume.
I'll put up a pic or 2 later on if you like and you can have a laugh