Originally Posted by Iceberg
The BW lubricates from the main engine via pump ontranny
If you're talking about the BW Velvet Drive this is not correct. The Velvet Drve marine gear is totally separate from the engine's lube system and in fact uses ATF, not engine lube oil.
However depending on the model of VD it may be permissible to operate a VD on engine lube oil, but there is still no connection between the VD's lubrication system and the engine's.
There may be other models of BW marine gears that do use the engine's lube oil instead of their own self-contained fluid but if there are I don't know which ones they are.