I've got a 2000 Acura 3.2TL. I normally change oil and filter every 4K miles however, the Users Manual stated to change oil every 7500 miles and filter every 15,000 miles. Any explanation for this requirement? particularly the mileage lapse between oil filter change? Most cars have a full flow oil system as opposed to a "by-pass" system. As such oil flow to the critical motor parts decreases over driving time. About half way between oil changes, the differential pressure (pressure in vs. pressure out) may have already increased indicating reduced oil pressure to the engine parts. In my '99 Ford Ranger, I change oil every 5K miles but change filters at the 2.5K mark. After all a good oil filter only cost $3.50. Your comments please.

What I recommend...is change oil every 3K. Thats 5000 KM if you're canadian. That is a severe duty maintenance schedule, and I think most ppl operate within it. It NEVER hurts to change oil more frequently than the schedule.