What type of oil is required for a BMW z3?

Answer 1

5W40 synthetic is what manufacturer recommends on their new line of BMW's.

This type of oil lasts longer, 10 000 miles, and lubricates better at higher rmp.

Don't change you oil at 3000 miles, it's a waste of money. Synthetic oil does not brake down at 3000 miles or lose any of it's properties. It has same viscosity and maintains it's additives well into 10 000 mile range. Castrol has detailed testing and graphs proving this.

You only change oil often, at 3000 miles, if using conventional oil, which with use and age, loses it's addtitives and viscosity goes up (yes becomes thicher with age thus restricting oil flow, and therefore does not lubricate properly).

Actually it's cheaper to drive on synthetic oil, due to gas savings and much longer oil change intervals, up to 3X longer.