When you have high oil pressure, this simply shows that lubrication would not be as efficient. "Good" oil has viscosity characteristics satisfactory to provide good hydrodynamic lubrication and flows freely around the engine, maintaining a continuous supply of lubricant. Lower oil pressure means that the oil is flowing swiftly around the engine, which is desirable in minimizing wear.
You need normal oil presure.If it is too high it could blow out a gasket or damage parts of the engine. If it is too low, that means some parts of the engine would not get enough oil to help protect moving parts. Check the owners manual and watch the gauges. In a commercial truck it should be around 30 to 60 psi. engine temp should stay around 110 to 120. listen for the fan to cut on whether it is a diesel p/u or large truck. Check the radiator fluid. see if there is any oil in it. check the tail pipe also for oil dripping. Always do a PM when needed." oil and lube" change all filters,Check all tires .Check all lights and other fluids from front to back including rear end hub grease and axle.