So I'm approaching 1k on the 390. I watch my gauges religiously. Up to this morning, Oil pressure ran about 70 +/- 5. This morning she was running about 80-85. Should I be worried? It was a little cooler this morning and truck never got above 186, where she been running about 190. I checked all the fluids, oil was fine with no signs of water in it, Water level was fine with no signs of oil in it.

 

I would say just keep an eye on it, and maybe consider a lighter oil. My 408 is doing the same thing. Nice hot day with 10w30 I was running around 60 psi when warmed up, smack on 80 dead cold (high 60s air temp). Now it's running about 75 psi warm (like yours, about 186~190) and will over run the pressure release in the oil pump when cold. I'm going to try some full synthetic 5w20 on my next change and see what happens. I'm also at 1000 miles on mine.

 

I wonder if the parts are bedding in an giving you a better seal between components, hence higher oil pressure.

 

You know the deal, stick a mechanical gauge on it, see what your real pressure is.

 

The pump is capable of putting out a LOT more pressure than the engine will ever need. I had a Honda Accord that the pressure relief valve failed, stuck shut..... You could start the engine, and the oil filter would instantly become spherical, and then blow out. Made a serious mess in VERY short order......

So long as you actually HAVE oil pressure, I wouldn't worry about it. I think the PRV will only let pressure max out at around 90, maybe.....