I always make a point to change my oil at least every 1500 miles. My friend told me that some oil impurities are good, and changing the oil so frequently is bad for my engine. I'm trying to prevent sludge and parts wear, obviously. The impurities lead up to this crap, don't they? What's the deal?

Also, do oil detergents really benefit my engine? I used to put them in my motor at every oil change, but I figured I was wasting my time and stopped buying it.

 

Its only harmful for the wallet... bt 1500miles is a bit over-doing it imho.

 

Changing it every 1500 miles is a waste of money, as stated. Pick a good quality oil and have an oil analysis done and you'll be able to tell how often you should change it.