It was tested with a gauge....25 cold...but thin old oil....owner does not wanna use the motor so he is not putting a oil change into it....i ran the boat from R.I. down......what are your plains for this motor.rebuild?[/QUOTE
Two points. The 6Bs are not known to have low oil pressures.. 12-15 psi @ idle hot is not unusual. If the gauge is reading 20 psi @ cruise rpms warm I'd be suspicious of the oil pressure sender and or gauge.
The 6Bs ARE known to be sensitive to too much oil and it's best to run 12-13 qts. MAX in the oil pan of 15w-40w with a Fleetguard oil filter changing every 100-150 hrs.