Stick with the interval stated in the manual. The dealer is going to try to get as much money out of you as he can. Yesterday I took my car to the dealer to get an oil change (deeply discounted to get me to look at new cars.) I had an appointment, but after waiting an hour, I went looking to see if they were working on the car. I found it still sitting where I had left it. No sooner had I got back into the waiting room, the service adviser comes to tell me that the tech had checked my car and it needed
1) Tires rotated 2) Wheel Alignment and 3) Cabin filter. I politely declined but wanted to ask if the tech was Clairvoyant. The Tires had been rotated and the cabin filter replaced within the past six months. The tires have 45K miles on them and are wearing very evenly with plenty of tread left. The steering wheel is perfectly straight and no pulling either way. I am positive that the alignment is correct. My position on alignments is -- If it ain't broke, don't fix it!! With the condition of many alignment machines that I have seen, you could very well be messing up a perfectly good alignment. I had once heard that there was a requirement to get them calibrated on some schedule, but I have asked a service manager (at an indy tire shop) about it and he said not. Any one know for sure and where?