How long do spark plugs last?

[Bob Of Burleson]

I've had a set in a four-banger for 65,000 miles and never had a problem. Should I change them?

[Kiamichi]

I replaced the ones on my Ranger at 100,000 although the mechanic said it wasn't necessary.

[Bob Of Burleson]

Notice any improvement in gas mileage?

[Kiamichi]

Notice any improvement in gas mileage?

Negative. The engine burns no oil and they were not at all fouled.

[Mark]

In today's cars, they may very well last the life of the car. I've seen them with over 200,000 miles and still going strong.

Unleaded gas and fuel injection makes everything in the engines last much longer.

[Grassman]

In today's cars, they may very well last the life of the car. I've seen them with over 200,000 miles and still going strong.

Unleaded gas and fuel injection makes everything in the engines last much longer.

Then ethanol fuel is dragging the life span back down.

[tx3653]

My 2002 Malibu still has the original plugs. It has never had anything done to it repair/tune-up wise. Maybe the main factor is not that it is 12 years old but that it only has 39K miles on it.

[PlanoSooner]

changed mine in my old tahoe at 150k and saw no improvement.

unless one is fouled, run with what ya got