The reason BMT recommends OWS is purely based on results. OWS is a new company in OZ, based in germany.
We underwent extensive testing on the dyno and on the track with a couple of cars before we would even cosider OWS. We were very pleased with the power gains and lower engine oil temps over most other oils.
Certain other oils will make more power, eg Redline, but need to be changed more frequently.
All factors aside, the main thing is use good fully synthetic oil, and change your filter & oil frequently...
Doc.