Hristo Tomov:

The best thing to do is to follow your owners manuals.

When my ISP comes back up (their server went down this weakened), I have a page that shows some comparisons and also what the numbers mean. It is at

http://members.net-port.com/~loub/car/oil_S.htm

All oils will be good at the operating temp of all engines. the difference is different viscosity (therefore different protection) at a high temp and different rates of evaporation.

To me, the best viscosity for MB and BMW are either 0W-40 or 5W-40 but they are not easy to find. 10W-40 is also good but only a few synthetic oils at that viscosity are available.

In Germany, the only available Mobil 1 oils are:

0W-30
0W-40
0W-40 Turbo Diesel
5W-50