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 #99249  by glennbp
 
Depends on the plug of course, but most newer premium plugs will go to 100,000 miles before requiring replacement.

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 #99269  by swalker
 
I changed mine on my 2000 at 43k and they were shot. Made a big diff.

 #99274  by screamingacorn
 
Thanks guys, I'm going to go ahead and do it.

 #99278  by sdmike300m
 
I did mine at 50k but didn't notice a difference

 #99300  by Mugs300M
 
I did mine at 80K but wished I had done them at 60K, if you have the cash do them.

Or, you can pull one to see what it looks like then make your decision.

 #99305  by Shadowvox6
 
IMO, the 100k mile thing is a fallacy. I have seen plugs that have gone 100k, and they are long since shot. My wife has a 95 Caprice, and one of my best friends has a 96 Caprice. Same motors (L99 - 265 CID MPI), same everything, except for 2 things....his car is OBDII, and mine is OBDI, and his uses Dex-Cool, mine doesn't. My car calls for plug changes every 30k, and has platinum plugs...his calls for plug changes every 100k and has dual platinum plugs. For AC-Delco, the dual platinum means there is a small piece os platinum on the ground, as well as on the electrode. Not enough of a difference to make the plugs last 70k longer. As a matter of fact, my wife's car is due for a plug change now....it has been about 30k miles.

Honestly, I would stick with 30-40k plug changes in our cars...it is easy, it is inexpensive, and is good insurance to have a car running in top notch condition.
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 #99352  by Avenger
 
I changed mine about 40 or 50k.......noticed the performance gains right away. Better fuel mileage too!

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 #99463  by velobard
 
I'm sure my car had original plugs when I bought it at 68k last Oct. I'm at 87k now and I'm looking to replace them in the very near future. From what I've read, I'd really prefer to jump straight to the Iridium plugs.

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 #100760  by Ruffy
 
Plugs are fairly cheap.
I'd honestly go 30-50k even if they're "long lasting" plugs.
You get that New plug feeling, Peppier car, Better MPG

 #100766  by tinman
 
I've often wondered how the mfrs. can say the plugs will last for 100k miles and your standard grade oil doesn't need to be changed for 7500 miles. Now that I think about it, I guess they just want to sell more new cars!
 #266344  by bwdave
 
I have a 1999 300m and I am a Newbie with this car. I was looking at the engine thinking that the top cover housed electronic spark plugs or something. I haven't bought the manual for it yet and am wondering if someone could fill me in on how to get to the spark plugs?

I have 141k on it and am sure it needs replacements.

Thanks for this forum and all your help.

:oops:
User avatar
 #266353  by 300maximilien
 
Welcome to the Forum!

Exactly 15 threads down from this one is http://300mclub.org/forums/viewtopic.php?f=29&t=22173 ..check out the second post in that thread.

It is recomehttp://300mclub.org/forums/viewtopic.php?f=29&t=22173nded to change them @100K....so you are a little overdue

'99s came with champions.....most here use the NGK both of which you can find part #'S for in this topic with a little searching
 #281592  by Shadowvox6
 
FWIW, I change my plugs once a year.
The NGK's come with a 3-year warranty.
I have a set on standby...one goes in, the old gets exchanged at Advance Auto Part under warranty, and goes on the shelf.

I have never bought into that 100k crap.
I have seen plugs that go 100k, and they wouldn't fire up a lawn mower (much like a Champion!!)
User avatar
 #281604  by LUNAT1C
 
I changed the Iridium plugs in my 03 Grand Prix SE (3100 SFI V6) with more Iridiums at around 90,000 miles. Old ones looked fine honestly. Worn, but fine. The car didn't feel or perform any better. New wires, too.

I changed the NGK's in my Special at 90,000 with new NGK. Old ones looked like they had another 10k in them. The car didn't feel or perform any different.

My Charger calls for new plugs 30,000 miles. People on LXF think that's a waste, as the plugs they're pulling out still look good. Most wait until 50,000. I am doing the same and currently sit just shy of 40,000 miles. Not looking forward to changing 16 spark plugs, but you gotta pay to play.
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 #281606  by Bill Putney
 
LUNAT1C wrote:...My Charger calls for new plugs 30,000 miles. People on LXF think that's a waste, as the plugs they're pulling out still look good. Most wait until 50,000. I am doing the same and currently sit just shy of 40,000 miles. Not looking forward to changing 16 spark plugs, but you gotta pay to play.
Huh? The Charger has two plugs per cylinder!? In my best Johnny Carson voice: "I did not know that."
 #281629  by isrb710
 
The 2000 FSM says to change them at 100K miles for both normal and severe operating conditions.

I changed my plugs at about 99,500 miles. Didn't notice any performance difference. Average gas mileage on the EVIC didn't change until the weather warmed up. (I had re-gapped them at about 83K miles, right after I bought the car.) I went with the Champion Platinum plugs that came with the car - since I got good performance out of the originals and they were about 1/3 the price of the NGK's.

I do NOT drive my car hard, so maybe that explains why they lasted 100K miles.

I believe the plugs to be the originals. None of the maintenance records I got with the car nor at the local dealership indicated the plugs had been changed.
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 #281630  by LUNAT1C
 
Bill Putney wrote:
LUNAT1C wrote:...My Charger calls for new plugs 30,000 miles. People on LXF think that's a waste, as the plugs they're pulling out still look good. Most wait until 50,000. I am doing the same and currently sit just shy of 40,000 miles. Not looking forward to changing 16 spark plugs, but you gotta pay to play.
Huh? The Charger has two plugs per cylinder!? In my best Johnny Carson voice: "I did not know that."
So I've been told. I've not removed the engine cover and looked as yet but modern Hemis were apparently designed that way since their first application in the Ram pickup truck.

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 #281632  by Tarheel
 
shadowvox6 wrote:FWIW, I change my plugs once a year.
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Why once a year?