? Max time/miles for original spark plugs

**Madness** · 09-09-2017

We have a 04 Grand Prix GT w/116,000 miles. How long can we stretch out the original plugs? Trying to save everything we can for a house, but dont want to have other car problems down the road.

Currently, we only put about 7,000 miles on this car a year.

What is the longest people on here have seen factory plugs go?

**cheatah faheatah** · 09-09-2017

Change 'em out already. It's short money for plugs. Mileage will improve, and improper combustion could lead to a clogged cat..... No Bueno

Now that's madness.lol

**coolone** · 09-09-2017

There are no plugs that last 100k, don't care what any manufacture says...

And honestly, you're talking $12 for plugs and you're worried about that? You shouldn't be driving a car if you cannot accept the required maintenance! At 110k you should have all you fluids changed, including transmission, brakes, probably rotors, all filters, etc. Do it yourself and save a bundle, and do NOT flush the transmission, it's a pan drop and filter or nothing. Your suspension is probably crying for renewal as well and more!

Good luck!

**Fivefingerdeathpunch** · 09-09-2017

That may be just opinion based but the modern Iridium and double platinum plugs are very long lasting. Can't tell you how many vehicles I've seen with will over 100,000 miles running them without issue. I still think the life cycle is 80-100k miles for how cheap they are to replace.

It's 12 bucks if you want to replace them in 2 years, copper core plugs are only good for 15-20k miles on a waste spark system before they show wear. Then it's $40-50 if you never want to do them again.

**MonzaRacer** · 09-26-2017

So $50 in maintenance will stop you from getting a house?

**blueguy91** · 09-27-2017

Put AL606's in it.

It'll last more than 20k miles.

If you're that tight in cash I would look elsewhere.

**MonzaRacer** · 09-28-2017

WHY does everyone keep recommending Autolite garbage. I work as a diag tech and take these damn things out ro cure misfires so often it amazes me the company is still in business. I have seen these create misfire issues in just about any brand of car out there. Heck neighbor brought his CADILLAC over the other day. Random misfires, ran like s*it. Took out Autolites he claimed cost him $2x.00 each. Went and got the appropriate ACDelco in and car quit missing. Was really worried about the converter melting down as it had missed so much but I think it will live.
My buddy was using the dang things in a $25k+ drag engine. They fought runnability issues for 2 days on dyno. Replaced the Autolites with AC Delco, ran great but his engine builder kept harping on how bad they were so we switched over to NGK.
Engine was VERY plug heat range sensitive, first set it lost power till it got good and warm, so we did some research and went UP 2 ranges and car liked that. Pretty much what I have found NGKs tend to run cool.
But then 30 yrs of working on and tuning engines means nothing I guess.
Good Luck but 100+k is toooooo long to go on plugs. Platinum and Iridium plugs can RUN 100k but I really dislike pushing ignition parts long miles. Tune ups are too cheap.
Factory plug is AC 41-101 Iridiums from factory and Autozone shows them for $7.99 and have $3.00 per piug rebate up until December http://contentinfo.autozone.com/znet...en_US/1709.pdf
Thats plugs that will go another 75K+ (reason I prefer earlier changes is the last half of plug life generally gives lower efficiency. ) for $4.99 each after rebate.

**Fivefingerdeathpunch** · 09-28-2017

Mod a 3800 and then you'll know why copper core autolites are the business.

Copper core plugs just plain old work in a 3800 when extra power in involved. It's the same with some LS power cars, copper core plugs are just good with high horsepower.

I ran copper plugs for over 4 years, changed them once a year for 12 bucks and never missed a beat.

If you want a plug for a daily driver or do not want to replace them alot go with Iridium plugs on a 3800, heck they even make factory iridium plugs for the CTS-V and Corvette/Camaro's that are cooler plugs that are run for boosted applications.

Autolites have their place, like with mopar hemi's or maybe a modded 3800 from time to time.

**coolone** · 09-29-2017

Monza, it's because everything that can be tried, has been in these engines! There's no unicorns left to find and its been found that as FFDP mentions, the Copper Core plugs work best on the 3800/L67 SC engine, no use fighting it. Lol

**LeadfootCJ7** · 09-29-2017

If you are asking, you should have replaced them already.

**MonzaRacer** · 09-29-2017

Not talking copper core talking autolites. I have tuned 1000hp n2o Chevy's/Ford's and have absolutely zero faith in them as NO manufacturer uses them oe.
I actually have better luck reading Ac Delcos on n2o. Just look for bubbling on ground straps. Every other plug except NGK just melted. Well Ford's seem to like MOTORCRAFT. And I know AC had autolites assembling plugs back in mid/ late 90s and we has so many that were dead out of box. Just my my experience.

**Roofus** · 09-29-2017

RockAuto.com I'd your friend. I changed all my plugs at 97k miles and got the most expensive Bosch plugs they offered. Only cost me 3.30 for two plugs, so right under $10.