How often do you change the spark plugs?
 

I know the plugs are $75-100 a set. I wondered if anyone changed them out once a year or less.

My car saw a significant boost in performance when Mazda put new plugs in at 6000 miles. At least it was a perceived boost.



So how often do you change the plugs? I'm not refering to the standard service at 37k. Odd number that :P and why doesn't my schedule show it again at 74?



:)