i have a 1994 6.5 diesel with 221k.. i was wondering what the norm was for oil pressure..at first cold start i am at about 40psi but after driving about an hour it will go down to about 32psi will driving 55mph at 2k rpm...and as i stop it will go all the way down to around 15-16psi

 

healthy engine should be about 20 at warm idle and around 40 or so at speed.

Yours sounds about normal for an engine with some miles on it.

Maybe a touch low at hot idle.

Sometimes oil pressure senders get inaccurate with age.

Although I'd say yours just sounds like expected engine wear.

What viscosity are you running? 15W40?

 

yeah im runnin rotella 15w-40

 

I'd say it's just your mileage that's got the pressure a touch low.

Your mains or rod bearing clearances are probably opened up a bit causing lower pressure. Maybe compounded by a bit of wear in the oil pump rotors/backing plate.

I wouldn't worry about it too much unless it takes a dramatic dive on you.

I wouldn't spend any money on it, unless you want to toss 60-odd bucks at it in a new pressure sender. But you'll probably see the same pressure after the change and essentially be throwing that money away....

FYI, the 6.5 has a pressure relief that is supposed to hold max pressure around 40 PSI. Some can see higher on cold starts depending on temperature and oil used.

My Optimizer 6500 (around 10,000 miles on it) can spike 50-ish on a sub zero start but comes down to 40-ish after it warms up. I can see 25-ish psi at hot idle. That's with Rotella T6 synthetic, 5w40.

 

mine always reads 60-70, but i think thats because the OPS is junk

the one before read 20-40

and this one i have now read 40-60, but it **** out and now reads higher.

just keep oil in it you'll be fine