Outer Limits 4x4 Board

For the past couple of months I've been concerned about my '77 v8's oil pressure.
It varies from either full scale to about half scale or anywhere inbetween not dependant on load, temperature etc.
I checked oil level, flushed engine, changed oil x2 still the same.

Yesterday was a bit chilly so I put the heater blower on and you've guessed it, the oil pressure dropped to half scale.........I should have known better, time for a re-wire and a mechanical oil pressure gauge!

Mechanical guage would give you a more accurate reading and make sure it is not a sensor fault. The sensors are in a terrible position and easily get damaged.

The other thing it could be is the pressure relief valve in the oil pump. The can often stick but I don't know much more about them.