Personally I change the oil every 7500k whether BMW likes it or not. The ease is that both my X5 and Z4 are 3.0l engines. Same filter, same amount of oil. I get the oil and filter at the dealer, they give BMWCCA members 10% off on parts so that helps a bit. It's easy to do and gives me peace of mind since I tend to keep cars along time. I love going years without a car payment! JMHO