Spark plug change intervals?, Are plugs time "sensitive?"? Options

[draganc]

Let's assume your engine is well running.
How often do you have to change the plugs if you drive only 4-5k mls per year?

Any difference between older air cooled and h2o engines?

Thanks for the inputs!

[aircooledtechguy]

Don't sweat the plugs. I would change then at the same time you change your cap/rotor/points. Around 15K miles unless there's a problem traced back to them (which is rare).

Every time you pull the plugs you needlessly risk X-threading them in the Aluminum head. This is more common than most folks will admit to. I typically change my plugs/cap/rotor every year or two. My car is a really good running L-jet car with over 350K miles on it But I typically put 15K-20K per year on my car too, so I typically go well beyond what the book says. They still look pretty good when they come out too. It more depends on the running condition of the car than anything else.

BTW, I have never gotten mileage like that out of a set of plugs from an engine I ran carbs on.