Why does it matter? How much do you need?
This month we went to a call out where a healthy motor dropped oil pressure for no reason. The motor was fine when stone cold but as soon as the oil warmed up the pressure dropped out to around 5 psi. We started with a simple fix of checking relief valve inspection but all was good there so we had to check the bottom end of the motor.
The big ends and mains were in good condition and they didn’t really explain a drop in oil pressure so we kept digging and found that a piston cooling nozzle had come adrift. We replaced them as a set and gave the motor some bearings and rings while we had it apart.
We then re assembled the engine and found the oil pressure restored to 40 psi at idle. The motor has been running perfectly now for a couple of weeks.
Diesel engines like good oil pressure to protect moving parts that are under high stress.
This navara engine seized after the sump got staked and ran the engine dry.