Well, without saying too much here that could upset anyone.

The TWS is the better oil, formulated firstly for BMW's M series engines or at least 3 of them. TWS is not the same, it contains group IV/V basestocks giving it higher HTHS numbers. The RS 10w-60 (which incidently I sell) is a group III oil which is basically a hydrocracked or modified mineral oil, not a group IV (pao) or V (ester) synthetic.

If you'd like to drop me an email off the board I will explain further.

Cheers
Simon