Sparkplugs

If you've got 90K trouble free miles out of a set of plugs I'd buy *exact replacements*.

Seems unlikely that GM is putting NGKs in at the factory so I'm guessing he didn't get 90K out of the original plugs. I'd put in a set of whatever the factory DID put in originally.

He could have got it used. He said it has 90K with those plugs. The vec could have lots more miles on it. If used, The other person could have put them in before selling it.

I would buy the same one's that are in in now.

I should have been a bit more specific. I'm the original owner since

10/00. Plugs are *OE* with both NGK PZTR5A15 and AC-Delco 12567759 stamped on them. New AC-Delco Iridium 41985 plugs are about $6. while the Denso's are $12. Seems like I'd be wasting $48. unless the Denso's last 200k mi.

Personally I would use what the manufacturer uses. I think chevy comes from the factory with AC Delco. Gm engineers say that the engine was designed based on OEM parts and would take this thread real serious. I have had bad luck with Champion, so I avoid them.

Ah. I'd probably just use the same plugs again because I like to check how the plugs look every 50 to 100K miles and then put a new set in. I've seen several cases of "100K" plugs not making it past 50K so I really would be surprised to get more then 100K out of a set of anything.

had a problem with the cheap Bosch platinum's, the electrode slide out of the insulator .

It's hard to argue with success. I'd be putting in another set of what comes out.

I'm partial to the platinum plugs, but I can't really say why. I avoid the multi-tip plugs because they have a huge snake-oil quality surrounding them -- spark plugs send a spark from the supply electrode to ground, and one tip or many, there is still the same ground potential.

Your plugs have gone 7 years and 90k miles, that seems like something you would want to repeat.