Most systems (depending upon the desired flow rate of the BP relative to the total system capacity) will be anywhere from .050 down to .030. I would recommend starting smaller and working your way up to the desired flow rate.
The act of preventative maintenance, in and of itself, is FAR MORE important than brand/grade/base choices among lubes and filters.
- under maintaining something is akin to abuse/neglect; that can kill equipment by shortening the lifespan
- over maintaining something has never been proven to be anything but a waste of time and money