Spark plug replacement interval

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cchase

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I take care of a 2002 Chevy Malibu. It has 94,000 miles on it right now and it has the original spark plugs and wires on it. The owners manual says 100,000 miles on the plugs.

I took out the front 3 plugs a few days ago just to take a look at them. First impressions are that they don't need to be replaced, no deposits, discoloration, tips look new, gap was at spec. There are no drivability issues.

My question is, other than "peace of mind" is there any reason I should change them out?
 
Originally Posted By: cchase
My question is, other than "peace of mind" is there any reason I should change them out?


8 years and nearly 100k is a lot of time. There is a certain point at which you should draw the line, as spark plugs seizing in the cylinders is not unheard of.
 
Originally Posted By: The Critic
Originally Posted By: cchase
My question is, other than "peace of mind" is there any reason I should change them out?


8 years and nearly 100k is a lot of time. There is a certain point at which you should draw the line, as spark plugs seizing in the cylinders is not unheard of.


I use anti-seize on all spark plugs I deal with and dielectric grease on all electrical connections so seizing in place should hopefully not be an issue. Other than that, any thoughts?
 
Originally Posted By: cchase
I use anti-seize on all spark plugs I deal with and dielectric grease on all electrical connections so seizing in place should hopefully not be an issue. Other than that, any thoughts?


Considering the effort to take out all of the plugs and coat them with anti-seize, I would just replace them.

On a side note, anti-seize should not be used on spark plugs. I understand this is a controversial subject, but both GM and NGK recommend against using anti-seize as it simply is not needed and also increases the chance of issues caused from overtightening. Spark plug threads are already coated so there is no need to use it.
 
Originally Posted By: The Critic
Originally Posted By: cchase
I use anti-seize on all spark plugs I deal with and dielectric grease on all electrical connections so seizing in place should hopefully not be an issue. Other than that, any thoughts?


Considering the effort to take out all of the plugs and coat them with anti-seize, I would just replace them.

On a side note, anti-seize should not be used on spark plugs. I understand this is a controversial subject, but both GM and NGK recommend against using anti-seize as it simply is not needed and also increases the chance of issues caused from overtightening. Spark plug threads are already coated so there is no need to use it.


It's funny you mention that, I actually originally worded my post with (I realize it's a controversial subject, but...) and then changed it.

I have used anti-seize on my vehicles because I've had to deal with too many spark plugs stuck in place (on others vehicles). I would never suggest it to anyone else given some recommendations specifically aimed at discouraging the practice but I stand by my own choice because it keeps what can be an expensive problem from happening. As far as over-tightening, anyone can be ham-fisted, anti-seize or not.
 
Originally Posted By: The Critic
Originally Posted By: cchase
I use anti-seize on all spark plugs I deal with and dielectric grease on all electrical connections so seizing in place should hopefully not be an issue. Other than that, any thoughts?


Considering the effort to take out all of the plugs and coat them with anti-seize, I would just replace them.


It's not the 3 front plugs that require the effort, it's the three back plugs that can be an ordeal on many V6 cars. I say decide what you think the maximum life of this car is and if you are over halfway there, then replace them, b/c you gotta do it sometime. so maybe wait til 125-130k.
 
I replaced my spark plugs on 02 GrandAM twice at 50k and 95k. Both times I noticed a significant improvement at idle. Engine generally felt much smoother. Those spark plugs are also rated 100k. I think that depending on the car anywhere between 40-60k is a good interval even for iridium plugs. They can definitely last longer than that, but fuel economy and general engine feel can suffer.
 
The platinum plugs have lasted me 90,000 miles and roughly 5 years with lots of cross country driving.
I imagine Iridium's would last longer if you let them, just never dropped the money on them as I really don't drive that much anymore.

Although that may change. I'm in a job transition and the opportunities that are opening up could make a long commute.

If you have iridium's I would leave them. They are supposed to last 100,000+ miles.
If they are platinum's I would dedicate a Saturday to do it. As my experience is around 100K miles you will have a misfire code pop up and your check engine light will come on.
 
We generally follow the manual, but I have run OEM GM plugs over 200k miles without any issues in their 6.0 gas V8's.

It has a great deal to do with the ignition system in the vehicle.
 
Originally Posted By: SteveSRT8
We generally follow the manual, but I have run OEM GM plugs over 200k miles without any issues in their 6.0 gas V8's.

It has a great deal to do with the ignition system in the vehicle.


On my previous vehicle, an 04 Chev Avalanche with the 5.3L v8, at 60k miles the spark plug wires were welded to the spark plugs. The first two had to be torn to get off. I replaced those with factory wires, and cancelled the plug change because I was planning on selling it 6 months later. I was doing the job just for fun and it ceased to be fun at that point.

Just be aware on some GMs this can be an issue and it would be worth pulling those wires off sooner for a little dielectric grease as preventative maintenance.
 
Originally Posted By: Jim 5
Just be aware on some GMs this can be an issue and it would be worth pulling those wires off sooner for a little dielectric grease as preventative maintenance.


Good advice and this was one such case. The boots were fused onto the plugs pretty good for me, I always worry about tearing something and since the car is on a 600 mile trip right now I didn't want to risk removing the back 3 in case something did tear. I'm not man enough to feel like spending a rainy January day outside replacing plug wires.
 
If you want fun do that change on a Savana van!

We've had dozens of them, always run them pretty much 250k minimum, and more than a few have run that entire duty cycle without any plug or wire issues at all!

No avalanches here, but plenty of Silverado juju. Can't recall ever having any plug wires being that big of a deal to remove. Sounds like an isolated incident to me.
 
Originally Posted By: SteveSRT8
If you want fun do that change on a Savana van!

We've had dozens of them, always run them pretty much 250k minimum, and more than a few have run that entire duty cycle without any plug or wire issues at all!

No avalanches here, but plenty of Silverado juju. Can't recall ever having any plug wires being that big of a deal to remove. Sounds like an isolated incident to me.


Yes, it was pretty weird. Never happened to me before, but the GM parts counter guy says it's pretty common. The only unusual conditions we have around here is cold weather and road salt. Could be something to do with the salt, I don't know.

Cchase had the same experience with fairly cold winters and if I'm not mistaken the North East of the US gets its share of road salt (which isn't actually "salt"). It seems like its the only thing our vehicles have in common, and that you wouldn't get down in Florida.

I'd be interested in knowing what causes this. I ruined 2 different wire pullers before I tore the leads off.
 
I suspect that with the thermostat tightly closed and the mixture rich in icy conditions the cylinder head runs extra hot.

Just a guess. While tha factory leads are made to stay on well, mine have all come off intact(the few I mess with!).
 
Originally Posted By: cchase
I take care of a 2002 Chevy Malibu. It has 94,000 miles on it right now and it has the original spark plugs and wires on it. The owners manual says 100,000 miles on the plugs.

I took out the front 3 plugs a few days ago just to take a look at them. First impressions are that they don't need to be replaced, no deposits, discoloration, tips look new, gap was at spec. There are no drivability issues.

My question is, other than "peace of mind" is there any reason I should change them out?
Yes. Change them out. Every time you pull a plug,you risk a seize or cross thread,therefore,the fewer times you pull your plugs,the less risk. I never pull,inspect,then reinsert a plug. If an old plug comes out,a new plug goes in. Hope this helps.
 
Plugs can sure go a long time in some cars!
Quite a few have been left in for much longer than 100K with no problems at all.

But since you asked, I would change them. But get EXACTLY what is in there now!
 
I just ordered a set of Denso iridium tip plugs for my Tacoma. At 30K I used those for 60K then went back to stock plugs. I'll keep these for another 60K.
 
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