When to Change The Plugs

[byfalisha]

Forum...bought my G in summer of 05 with 51K miles...when should I be thining about changing the plugs? No noticable miss fires.

[joe603]

You should be good 'till about 80-100k. The OEM plugs are very high quality.

[pfarmer]

Forum...bought my G in summer of 05 with 51K miles...when should I be thining about changing the plugs? No noticable miss fires.

I used to have to change plugs about every 10k miles on my older rigs, I haven't changed plugs on but one vehicle in the last 10 years. However on that one it was a challenge. I think you probably can go about 100k assuming you are what I would refer to as an average driver (not necessarily average 'G' driver).

I need to do so on my 300 m as it has now acquired 149k miles and while running well I think I may be pushing my luck. One thing I found out with my last experience was that they had been in there too long and were hard to remove. No choice due to a broken insulator on one. I am not sure on what the 'G' has for the plugs but if you have an aluminum head without inserts then plugs can tend to seize. Another advantage about early changeout is you get a good view of indications of possible upcoming issues with the engine.

Perry

[byfalisha]

Thanks! Perhaps I'll make it a Memorial Day weekend honeydo!

[Poyzinous]

These newer generation vehicles recommend changes at 105,000 miles. Spark plugs begin to fall below their 90% spectrum at about 90,000 miles. Thats a good time to change them. Those who drive with a heavy foot should consider doing it every 60 or so. I will.

[tollboothwilley]

Most people have found that around 60K miles the gaps are not even. I'd recommend changing every 50-60K miles. Its easy enough...(and relatively inexpensive considering most parts for the car)

[pfarmer]

Most people have found that around 60K miles the gaps are not even. I'd recommend changing every 50-60K miles. Its easy enough...(and relatively inexpensive considering most parts for the car)

I think they should go much further than that for the average driver (not necessarily average 'G' driver from this forum).

But if nothing else, if you are planning on keeping the car for another 100 k or so, then changing the plugs now may be cheaper than changing the plugs later and gives you a baseline of what maybe had occured with the previous owner. If they are in good shape then you just paid for some info and piece of mind about the overall condition of your car. Based on what you see you may want to make some changes such as maintenance schedules, etc. You had it for how long (4 years) and what are the miles now?

Perry

[tollboothwilley]

Many people have found leaking valve covers when they change out the spark plugs...and most people that have changed them out before the 70K mark when the warrany expires have also notice differences in spark gaps as much as 20-30mm.

No harm in changing the plugs earlier...only benefits.

[pfarmer]

Many people have found leaking valve covers when they change out the spark plugs...and most people that have changed them out before the 70K mark when the warrany expires have also notice differences in spark gaps as much as 20-30mm.

No harm in changing the plugs earlier...only benefits.

He had 51k 4 years ago if he bought it in 05 with 51k on it by the sounds of it.

Are we sure we are speaking of most people or most people here?

Perry

[tollboothwilley]

I'm speaking for MOST people with a G35.

On several forums... for this engine I have seen many spark plugs at 60K miles. I would say that everyone should change them at 50-60K intervals to keep optimal performance.

I'm sure with your 2008 you probably haven't run into any issues and certainly haven't changed out yours yet. I've changed mine and many of my friends all with basically the same result.

[pfarmer]

I'm speaking for MOST people with a G35.

On several forums... for this engine I have seen many spark plugs at 60K miles. I would say that everyone should change them at 50-60K intervals to keep optimal performance.

I'm sure with your 2008 you probably haven't run into any issues and certainly haven't changed out yours yet. I've changed mine and many of my friends all with basically the same result.

You just made my point as most people who have 'G's probably don't bother to post to forums. And of those that do the ones that post are the ones that have reasons to believe they need to change their plugs early.

Most modern plugs can easily go close to the century mark under normal driving conditions and I doubt most drivers do not drive like my perceptions of how most in these forums do.

How often does Telecom change his plugs? That would probably be a good indication of how often you have to.

Perry

[tollboothwilley]

I have several friends that are not on this forum Perry. 350z and G35 alike...these are the ones I am speaking of. Plus I have also talked with many people who have more experience with hundreds of vehicles with the same results.

I'm not saying that you can't go 105K miles like the manual states...just stating that it is beneficial to change earlier.

[pfarmer]

I have several friends that are not on this forum Perry. 350z and G35 alike...these are the ones I am speaking of. Plus I have also talked with many people who have more experience with hundreds of vehicles with the same results.

I'm not saying that you can't go 105K miles like the manual states...just stating that it is beneficial to change earlier.

And the proven benefit is? I hope you really didn't mean 20-30 mm as stated earlier. that would make for a real long plug.

As far as Infiniti goes I would think that logic states they would actually be conservative in their recommendations not doubling it.

Perry

[pfarmer]

Thanks! Perhaps I'll make it a Memorial Day weekend honeydo!

Just to let you know that Telecom is at about 88888 miles and counting. He states that his gas mileage is doing well and he uses that as an indication of how well his car is performing. I agree with this as a good criteria with the only additional statement that I add is under load. Typically a couple of times a week I will listen to the car when cold and when hot at the exhaust. If everything is ok, mpg, under load performance, and sound doesn't indicate any issues then I would consider leaving them alone.

How often you need to change is of course related to how hard you push the car but if you are a 'normal' driver I believe you should get 100k or more out of a decent set of plugs. If you race all the 'H' cars in the neighborhood on your way home from work then maybe every 5k is not often enough. Just pay attention to the criteria I mentioned and maybe some others of your own and change them when they need to be changed.

Perry

[chasracer]

Plugs are cheap, easy to change and certainly worth the effort. Don't skimp on the quality of the plug either, top-notch name brand plugs with at least a platinum tip would be the lowest level of sparkplug that I would even bother with using.

50,000k is a good service number, you will have gotten your money out of them and also had a peak at engine condition. If you run your car hard more often than not, consider dropping down one number to a colder plug too.

[tollboothwilley]

Just to let you know that Telecom is at about 88888 miles and counting. He states that his gas mileage is doing well and he uses that as an indication of how well his car is performing. I agree with this as a good criteria with the only additional statement that I add is under load. Typically a couple of times a week I will listen to the car when cold and when hot at the exhaust. If everything is ok, mpg, under load performance, and sound doesn't indicate any issues then I would consider leaving them alone.

How often you need to change is of course related to how hard you push the car but if you are a 'normal' driver I believe you should get 100k or more out of a decent set of plugs. If you race all the 'H' cars in the neighborhood on your way home from work then maybe every 5k is not often enough. Just pay attention to the criteria I mentioned and maybe some others of your own and change them when they need to be changed.

Perry

I understand that you can go the distance on the plugs. Hell, you can drive on tires for thousands of miles past their wear bars too...

NGK are the recommended plug.

I would go with either the Iridium IX or the Platinum. They run like $9-11 per plug.

[pfarmer]

I understand that you can go the distance on the plugs. Hell, you can drive on tires for thousands of miles past their wear bars too...

NGK are the recommended plug.

I would go with either the Iridium IX or the Platinum. They run like $9-11 per plug.

Note that tires past their wear bars start to get dangerous and you experience a decrease in performance.

What I am stating that if you don't experience any problems there is no reason to change you plugs beyond possibly analysis of you engine. If you are maintaining gas mileage, get the performance you should under load, and have no indication of a problem by listening to your exhaust and whatever criteria that floats your boat, you have little reason to change them.

Perry

[telcoman]

How often does Telecom change his plugs? That would probably be a good indication of how often you have to.

Perry

Not very often!

I will turn 90k this coming week. I have no intention of changing my plugs as I am consistingly getting over 25 MPG on regular 87 octane.

My G is just purring along.

I watch my gas mileage very closely and change my oil religously every 3-3.5k miles with Dino 5w-30 oil whatever is on sale



I have discovered that temperature and humidity have a greater influence on MPG than the grade of octane used.

Telcoman

[rpm240sx]

HAHA why are we getting so dramatic about changing plugs? If you drive hard and feel like spending a few bucks on some good ol' preventative maintenance then go for it. If you feel the need to wait and do what the manual tells you then by all means wait. I understand the point of, "if it's not broke don't fix it" but if you have the wallet and don't mind preventative maintenance and like to play it safe then change your plugs. I myself change plugs every 50-60K I too have a heavy foot though.

[TISon28s]

About every 40k miles .

[pfarmer]

HAHA why are we getting so dramatic about changing plugs? If you drive hard and feel like spending a few bucks on some good ol' preventative maintenance then go for it. If you feel the need to wait and do what the manual tells you then by all means wait. I understand the point of, "if it's not broke don't fix it" but if you have the wallet and don't mind preventative maintenance and like to play it safe then change your plugs. I myself change plugs every 50-60K I too have a heavy foot though.

I believe it is simply a waste of money, time, and also unnecessarily exposes the heads to possible damage as well as cylinders to fod if done incorrectly when there are no indications that plugs need to be changed out. I believe an average driver should be able to get close to 100k without issues. Of course if they need to be changed early then every 5 k may not be too soon for some.

Perry

[Poyzinous]

you change plugs when the engine is cold. You dont need to worry about damage at that point. You can run a few simple tests to know if your plugs have deteriorated a little earlier than normal. I drive hard, and as a tech, I dont want to run my plugs to the limit, so I'll change them soon Probably after my next oil change.

[blacksrjdm]

According to Nissan they are 105,000 mile plugs...The part # is 22401-5M015. The list price is $11.00 each. They are pregapped and installation is rather easy. Here at the Nissan Dealer we recommend them around 90,000 miles. Hope this helps. I am not sure where alot of these people are getting there info. but all this 30,000 - 40,000 miles or any of that is just too soon. I would say that if you are at 51,000 miles, wait another 40,000 before changing them. Maybe take them out and check the gaps, although if the car is running well, then I wouldnt worry.

[pfarmer]

you change plugs when the engine is cold. You dont need to worry about damage at that point. You can run a few simple tests to know if your plugs have deteriorated a little earlier than normal. I drive hard, and as a tech, I dont want to run my plugs to the limit, so I'll change them soon Probably after my next oil change.

I haven't looked at the Nissans for how the damage could be done, yes the plugs should be cold for the benefit of thermo expansion. However I have seen problems with dissimilar metals as well and damage can occur not only on removal but on insertion. On newer engines the dissimilar metals should not be a problem on removal since this was a bigger issue with the original aluminum heads especially those without inserts and older style plugs. I have seen a lot of articles describe putting various 'Never Seize' types of applications to prevent seizure. This can be a fatal mistake as many products can actually enhance the interaction between dissimilar metals instead of preventing it. Helicoils was often the ultimate solution when things went bad.

As a tech you are most likely far more aware than most of the backyard mechanics are about not only removal techniques but proper insertion and torque. The same goes for fod, something I have seen overlooked even by those that should know better.

The one other item for those who are used to wires is the coil packs.

I am not stating in any way that one should not change them before failure, just that there really is no need to change them out far earlier for the 'average' driver. To do so exposes the vehicle to these possible problems.

Perry

[Poyzinous]

Sounds good. But lots of the guys here driver harder than average...as long as you do your work exactly like it should be done per the ESM, you'll be fine. Here at the dealer its recommended at the 105,000 mile service, sometimes 90,000. The ignition coils only need replacement upon failure though. I'll probably warranty those though

[Poyzinous]

Sounds good. But lots of the guys here driver harder than average...as long as you do your work exactly like it should be done per the ESM, you'll be fine. Here at the dealer its recommended at the 105,000 mile service, sometimes 90,000. The ignition coils only need replacement upon failure though. I'll probably warranty those on my car at about 85k or so

[pfarmer]

Sounds good. But lots of the guys here driver harder than average...as long as you do your work exactly like it should be done per the ESM, you'll be fine. Here at the dealer its recommended at the 105,000 mile service, sometimes 90,000. The ignition coils only need replacement upon failure though. I'll probably warranty those though

As far as the coils I was referring to those who are not as careful as they should be with them.

Perry

[SVTCOBRA]

My coupe now has 56K miles on her.

Decided to check the valve covers to see if they were leaking.http://forums.g35club.org/zerothread/355022

I WOULD ENCOURAGE EVERYBODY TO CHECK THEM BEFORE THEIR POWER TRAIN IS UP. as was mentioned earlier.

Anyway, decided to go ahead and change the plugs since my experience has been that they will be out of gap, and they were. Otherwise, they looked OK.

Car idles a little smoother now, not that it was really rough before.

I also can tell that it has gained back 3.47 HP that it had lost!!!

So, the lesson of the day boys and girls is, if you plan on keeping your car past the Power Train Warranty end date AND will not be covered by any other warranty, go ahead and check those valve covers.

AND, since it is a minor pita to do, go ahead and change those plugs while you're at it. You will thank me when you go WOT!!

Back in the day, I think I was changing my plugs and points monthly!!!

Oh, and my valve covers are not leaking!
Modified by SVTCOBRA at 1:58 PM 7/25/2009

[G_whizz]

Great post Rich.



Something I would probably forget to check before my waranty runs out.

Actually, we should make up a checklist of things to do/check before warranty goes for future reference.

Is this why your back hurts??

lol

[SVTCOBRA]

Thanks & Yes!! I am only a mechanic on TV.....IT crap is my real job, so I can be rather sloooooow!! And, picked enough green beans for another 7 qrts!!