Hahahaha. This certainly is a hot topic. A hot topic on any car forum. Let's consider that tractor trailer trucks don't have regular oil changes shall we? They simply get an oil analysis every so often and those engines last hundreds and hundreds of thousands of miles. To say that the guys at the oil change shops know more than the engineers who designed the engine is a stretch. Both are trying to make money off you of course.

Myself, I change according to the manufacturer recommendations or when I notice a problem. I had Amsoil transmission fluid in my last car and it lasted 90,000 miles. And I'm going to use Amsoil synthetic fluid in the X3 when the warranty runs out. It has a one year/25,000 mile life span, but only when used with their Ea series filters which are not available for the X3. : (

To each his own, but don't get offended by other's opinions. : )

Cheers.