Spark Plug Time over Mileage

[cadfaeltex]

I was reading through the spark plug anti-seize thread (this has NOTHING to do with anti seize) and noticed some saying that time on a spark plug is more important than mileage. Both of are cars see much less than average mile a year (5K tops right now). What is the rule of thumb for time on plugs? Does it matter on the engine and the plug?

For reference:
2007 Acura MDX - orginal plugs, 36K miles total on vehicle
1994 Jaguar XJS 4.0L straight six - champion plugs (original #), 90K total miles and approximately 3K on the plugs in 9 months since changing them.

 

[CATERHAM]

I've never heard of a time limit on plugs.
I'm running some plugs that are twenty-five years old without issue.

 

[NHGUY]

I change plugs every couple years no matter how "precious" the material or mileage.Its good insurance.Ford Triton owners should follow that same regimen.

 

[HTSS_TR]

The recommend spark plugs change interval of my E430 is 5 years or 100k miles. When it was changed 5 years ago at 7 years and 8x,xxx miles the plugs were almost as new, but I already bough the replacement (16 plugs total) so the new pugs were installed. If I didn't have new plugs I could safely re-use the old plugs.

The Bosch plug for E430 was expensive at $8.xx each online, 16 of them is good $.

 

[Corvette Owner]

Don't see how time would affect spark plugs? They are in a pretty protected environment when not being used.

I know that Iridium Plugs are GREAT. I took a set out of my daughter's Chevy Malibu with 105,000 miles on them and they looked like new! It's the only plug I will ever use.

 

[ahoier]

I've never heard of a time limit/restraint on plugs.....though I can sort of understand what they're coming from....I guess the off chance the plugs could get stuck in the engine or something...? Only reason I could see going by time....sure, maybe on an old weed whacker that only gets used once or twice a year....but not on a daily driven car....hehe.


Then again, a daily driven car will likely hit the mileage mark before the time mark (if there is one)

 

[gathermewool]

If there's a time limit, then my guess is that it has more to do with presumed driving habits, not time itself. In other words, the OEM might assume that a low mile-per-year vehicle sees a lot of stop and go and idling.

 

[The_Jeff]

Idling should be easier on plugs, takes less energy to make spark at idle than it does under load.

Of course, you're still dividing by zero MPH.

 

[mechtech2]

I never heard of time being a factor, either.
There is no wear when sitting on the shelf or installed in the car.
Maybe the idea comes from a general common understanding of how many miles are accrued each year on average.

 

[exranger06]

I think what the OP is concerned with is, if spark plugs are left installed too long, they may seize in the head and break or strip the threads in the head. Of course spark plugs don't wear out because of time, but removing them makes time a factor.

I would like to know the answer to that as well, since my truck will likely be over 12 years old before it's due for a plug change.

 

[Schmoe]

News to me.

 

[Eddie]

Maybe the time limit has something to do with seizing in the head?

 

[SteveSRT8]

I realize that some of us live in the northern climates and deal with massive corrosion issues, but plugs do not seem to seize in our heads.

haven't had that happen since iron heads left.

 

[cadfaeltex]

I wasn't sure what the rational was when I read it but the seize issue might be it. I was especially concerned for my Jag with the aluminum head (AJ6).

 

[SteveSRT8]

aluminum is precisely the reason that seizing is unlikely

 

[gathermewool]

Originally Posted By: eljefino
Idling should be easier on plugs, takes less energy to make spark at idle than it does under load.

Of course, you're still dividing by zero MPH.

Agreed, and your last comment was my point. If a time limit is given, it may be conservatively assuming that you're doing a lot of idling, which may result in low annual mileage, but more electrode wear due to hours running.