Two and a half thou on main bearings is on the high end of new (.001 to .003 new .001 to .0045 used).
Cooling the oil will no do anything to increase pressure (pumps create flow, and restrictions create pressure).
As already stated, any pressure is good. 90% of wear is at start up. If you *really* want to alleviate wear, spend your money on a pre-oiling system. That will pressure your bearings before startup and wear is GREATLY reduced.
