Retouching on a prior question, on my 91 318 pwred beast, the oil pressure, to me, seems low. While driving, the pressure show to be about 1/8" or so of an inch off of the LOW-SAFE mark. Then, while at idle, the pressure drops to right at, or JUST a hair BELOW the LOW-SAFE mark.

Now, since I just bought the thing, I have NOT changed the oil yet, but am planning to do so this weekend. God only KNOWS how long it's been since it's been changed prior.

 

Like I said in the other post, that is not normal behavior for the engine. My pressure never drops below the half way point of the gauge, and on the interstate usually makes its way up to about an 1/8" off the high side line. It could be that if you have old oil in that truck it could have sludged and gummed up the pump. I would suggest that you change the oil, drive it 500 too 1000 miles, and change it again and then see how it behaves. But if your going to fix that freeze plug problem, go ahead and put a HV oil pump in... they only cost about $50.

 

I would verify poor oil pressure with a mechanical gauge first...