I change my oil every 2500 miles. It makes for easy math when on a 5K service schedule. I recommend my customers do the same thing, 2.5K on regular oil and 5k on synthetic. With customers I recommend this because if you tell them to come in every 2.5K you are doing good to see them in 4K and if you tell them 5K then it rapidly becomes 8-10K in pretty short order. If you go too long between services, among other things, it becomes tough to monitor stuff like brake pads and the like. It is easy to look at the pads and say yea or nay on whether the will make it to the next service but when the next service might not be for 10K or until next year some time it gets a little tough. Oil changes are pretty cheap insurance against a whole host of evils that can befall your car. If your speedo is broke then I simply recommend coming in every four months and have it changed out. It runs about $40.00 for a straight up oil change and safety inspection in my shop, $160.00 per year is a bargain if you ask me. I even know of a couple of shops that have gone to the lifetime free oil change program. You buy the program up front for $200.00-$300.00 and then you are locked in for 4 oil changes a year. The changes will be done at absolutely no cost to you 4 times a year. When you pencil out on paper and factor in advertising and people who go to Jiffy Lube instead it is actually a winner for the shop owner to give the oil changes away just to keep the customer in house!!

Mark