Merc 5.7 loses oil pressure, one manifold hot, white stuff on remote oil filter.

[jamanati]

Finally got down to my boat.
Hooked up mechanical oil pressure gauge on a tee fitting and kept electrical gauge connected. Both show pressure at idle at around 50-60 psi. Took it out for about 30-40 minutes, driving it at 3200 rpm, then down to idle, then up again, etc. Pressure maintained with no issue on both gauges, around 45-50 when at 3200 rpm and dropped to around 30-35psi at idle. So this is one strange issue.

[mmwjr]

No alarm?

Those pressure readings sound normal for those conditions.

[jamanati]

No alarm since the oil pressure remained fine throughout the day.