I changed plugs at almost 48k...stock AC irridiums at .040". The old ones all looked good...tan color and no signs of damage to the electrodes,etc.

I guess they could have lasted a lot longer but at least I got some indication of engine condition from the change. They all came-out easily. I put anti-sieze paste on the threads.

How long do you guys go on plugs on a stock engine?

 

You spent $60 changing spark plugs?!?!?!

Yes, I just buy the $2 Tr-55 NGK spark plugs at Advance or Autozone. Plenty of other people will back me up on that. I used to run them in my truck on nitrous and run them in my girlfriend's tahoe

 

the OEM plugs are good for 100,000 miles.

 

+1 to the NGK's. The Guy at the counter didn't wanna sell me them over the platinum tipped whatever that is OEM, but I just kept ignoring him.

 

Thank fully i run nitrous! my TR6 plugs are $1.89 each haha!!!

 

That makes 2 of us.

 

I can vouch for that. I purchased my truck at 74k and changed the plugs at about 109k and they were nubs. Apparently no one had ever changed them.

spent about $15 bucks on some NGK TR 55's and replaced em.

 

I don't think you wasted $60. I change iridium plugs in any of our vehicles at 50K and in the trash they go. Secondly, I can't speak for others but for myself I've never seen any spark plug work worth a damn in a GM vehicle that wasn't a genuine AC-DELCO plug. I always use Delco plugs and make sure you buy them from a GM dealer. There is a difference between an AC Delco plug you buy at an auto parts store vs. what's at the dealer. If no one believes me, I'll have to find the two plugs I have at home. Same delco part number. One from Champion auto parts, one from a dealer. The one from the dealer is at least a 1/2" LONGER.

 

Changed mine at 75k for TR55's. Truck started easier and ran smoother afterwards. The stock plugs didn't show a ton of wear though, just the normal tan color.

 

From what I have heard, NGK makes Delco's spark plugs...

And like I've said before, spark plugs are spark plugs. Put whatever you want in there as long as they're gapped right (and arent Bosch or Champion) and you should be fine.