Spark plug life?

[Roberto]

Just reading the couple of Spark Plug threads lately.

Does anyone know what sort of life span spark plugs have in our cars?

I had a set of Denso Iridiums fitted coming up to 50K miles ago.
Got them checked after 30K and they where in tip top shape.
And they are still running fine.

Thats heading on for 3 years (in March) in the car now.

Any ideas when I should think about changing them?
Or just keep running them?

[Nick Mann]

On the service schedule they are due for changing every 45k miles.

I have no concept of how much longer than this the plugs can last, so can't really help much more!

[Roberto]

Thanks Nick,

But is that not for standard plugs, rather than Iridium.
Not sure myself, hense the question.

[Paul Beazer]

Std plugs are platinum IIRC, which have a similar lifespan to iridium ones. quite glad they have such a long life, doing the rear bank is a real PITA!

[bradc]

lots of people say 60000miles for the iridiums, probably worth checking them soon and getting some new ones if you need them.

[Kieran]

Well, 45K is the standard interval. Iridiums are supposed to last an equal length if not longer but it depends on the car and it's state of tune.

Given that our engines run stupid rich (and every time I've pulled the plugs they've been sooty becase of this) I would stick to the specified interval (or sooner if you've upped the power) and inspect every now and again. To inspect the front three is easy enough and provided you're not hunting a problem I would say it's safe to just check the front three and use them as a yardstick for the state of the back three (unless you're getting close to a change interval). Obviously if the front three are knackered when you check them you'll have to bite the bullet and have a nosey at the rears.

[Fully]

You should get about 100,000km out of that sort of plug.
But that all depends on how your motor runs.

I will be changing mine when I do my cam belt, with the waterpump as well.

[d i c k i e s]

at our meet recently we did spark plug changes... think mine were shot! but noticed no difference? maybe i did a bit.