Well, if anyone here is changing there spark plugs every 10k miles then they should stop buying those cheap spark plugs from the 99 cent store. Get yourself a half decent pair of plugs and there is no reason why you can't get atleast 50k from a pair of spark plugs. I just changed my spark plugs last month for the first time after my car hit 102,000 miles. I checked the plugs that I pulled out and certainly did not appear as if I waited too long to replace them. Of course my plugs are not from the 99 cent store. I replaced them with the same plugs and do not expect to need them replaced for atleast another 85+ thousand miles.