Dealers Ignoring Spark Plug change intervals?

[tjkubota93]

The new Iridium plugs say use no antiseize, just torque correctly
The plugs are supposedly inherently antiseize. I guess we'll know in 20 or 30 years.

Chrysler v6 minivans a while back would misfire if you used anti seize. They didn't get a good ground through the threads if it was used.

 

[om21braz]

I just changed the plugs on my E450 V10. That was fun! Not!

That engine and the Cadillac Northstar would have you talking to yourself

 

[3930dave]

Back in the day it was common to change out plugs and points at 10k miles.

Cars have not had points since the 70's and spark plugs last a long time.

Recently I have been hearing dealers dissuading owners from changing plugs.

One of my friends took in his bought new and only dealer serviced 525i that is 15 years old and just hit 100k.... the dealer did not change out the plugs even though the service manual called for it.

My brother took in his Chrysler 300 which hit 60k miles and also calls for a plug replacement and the Dealer said they don't do that.

Sounds strange in this day when service writers are always trying to pad work orders...

Have heard of expensive head repairs when plugs were taken out hot or never taken out.

Any thoughts?

Plug life (rated) has moved out in the last 30 years to the point where many people consider them to be a No Maintenance item. Fine if you can afford to buy vehicles new, and unload them at less than 100k miles.

Past Due plugs (as others have stated) are a big factor in coil and even associated drive-electronics failures. Coil failures are relatively common on COP designs, relative to 30 years ago.

I don't like to leave plugs in for crazy long miles (driving older vehicles), so I use a decent to-spec copper core plug. If you look at the conductivity tables, it's only when you get to the latest-gen precious-metal plugs do they attain the same conductivity as copper-core ones. That issue doesn't matter to many people, but it can be a factor where I live when you are trying to start a car at -35 with a weak/old/discharged battery.

Yes, pulling intake manifolds to change spark plugs is a PITA - many older Escapes with V6s only ever get 3 plugs changed.

The only reason I can think of for a dealer to try and defer plug changes beyond spec is if there is a known problem with the head design (ex. - certain, now older, Ford pickup truck engines). The dealer may just get tired of fighting with the customer/factory/warranty company over who pays extra for fixing stripped threads.

I've talked with several people who have worked on Honda vehicle engines with something like 300k km on the original plugs. Not fun, and needless to say there wasn't much left of the plugs....

Power drive-electronics for coils can be easy to diagnose with a hard failure, but I've also seen soft/intermittent problems too...... if the vehicle is old enough, the thermal transfer compound on the heatsink may be worth checking; there wasn't much original compound left in place on my 1989 car a few years back.....

Rgds, D.

 

[ultrarunner]

^^^This is what came to mind that Dealers want to avoid problems due to bad experiences...

 

[Turbys_1700]

I would agree that most dealers are declining plug changes due to possible issues with stripped out heads. My wife's 98 Ford Contour just had a tune up. My mechanic changed out the plugs and wires. It runs fine now. I think the car is right at 130K miles. My old Buick Lesabre had the same procedure performed at right around 150K miles. These are the only two instances I can recall changing out the plugs and wires in 40 plus years of automobile ownership. Typically I keep a car and run it until the wheels fall off. The last three that I kept were sold or traded in at over 200K plus miles. Couple months ago I had to change out the plugs on my Toro Workman that has a tired 16 HP engine and occasionally I'll foul a plug in a chainsaw or weed eater. In my experience plugs get changed when needed, not as a part of routine maintenance.