Factory iridium plugs life span

[Whamhammer]

Hi all,

I know the factory iridium plugs are supposed to have a lifespan of 100k miles, but how long are they at thier best efficiency? I've had mine in my car since September 2009 and driven about 50k on them. With the age if them, I am not opposed to changing them, but I dont want to waste money, time, and effort if it wont help.

[SMWS6TA]

It really depends on several factors: Gas type, driving habits, duration of drives.

For me I start checking them around 70,000.

On my DD they needed to be change around then, on my sons car his needed them around 90,000 miles.


On the bird...never use them. I'm running a NGK TR6 now, the TR5's were too hot.

[Whamhammer]

It really depends on several factors: Gas type, driving habits, duration of drives.

For me I start checking them around 70,000.

On my DD they needed to be change around then, on my sons car his needed them around 90,000 miles.


On the bird...never use them. I'm running a NGK TR6 now, the TR5's were too hot.

I use Shell/Mobil/Sunoco premium for a 35 mile trip up and down 95 to Baltimore during rush hour,and occasionally do an Italian Tune-up. About an hours each way. I guess I should pull #1 now

[pajeff02]

I ran our Suburban spark plugs just north of 80,000 miles and they still looked to be in great shape.