Oil pressure mystery

[cranetruck]

Got a bit of a problem with my oil pressure I think.
I usually run with Texaco Ursa 30 weight, but after the new oil seal installation, I used the Shell Rotella 15-40 (from Walmart).

This is what happens: Right after starting the engine in the morning, the pressure shows about 40 psi. After 1/2 hour or so it drops to 25-30 psi and finally when I have been on the road for a while it drops to 15-20 and stays there for the duration of the drive.
There is plenty of oil in the crankcase and new oil filters (WIX 1133) were installed in Oklahoma, which had no effect.
I have been driving at least 2,000 miles like this and will change back to Ursa 30 weight ASAP.

Looking for comments.
Thanks.

 

[WillWagner]

I have a 120 PSI gauge. On the 1st oil change I used Chevron Delo400, 30 wt. The O/P was at 85 PSI cold, didn't believe the dash gauge, so I installed a quick disconnect fitting at the oil filter hsg. After it warmed up, hot idle pressure was 50 PSI, going down the road it was 60-65 PSI. Last change I used Valvoline Premium Blue 15w40 the pressure is 10 PSI lower across the board.

 

[2deuce]

My deuce does the same thing with oil pressure but a little more severe. When cold it runs about 30lbs and drops to 15 when hot. It been this way for the 4k miles I've put on it with no problems yet. I use Delo 400 15-40. My first oil change after I got it yielded a large chunk of metal that worried me more than just a little and makes me think that the low pressure and the chunk are likely related.

 

[clinto]

Rotella 15W/40, 465-1D

Cold = 60 lbs at idle
Hot = 30-35 lbs at idle
Hot = 50 +/- 5 lbs at speed

 

[jkelly66]

When I was on active duty I know we used 30wt but when I got my Deuce out of DRMO I found they had painted on the valve cover (engine oil 15w/40)

 

[alphadeltaromeo]

From what I understand about diesels, starting with lots of oil pressure initially is quite normal and after the engine has been running for a while, the pressure drops. My CAT track-loader has the same results. When I fire up the CAT, the oil pressure pegs the dial, but drops significantly once it has warmed up. My father-in-law has been a diesel mechanic on the left coast for 30 years and shared that with me when I asked the same question about what I was seeing. Hope that helps - Andy

 

[Stretch44875]

I run 15w40 rotella, and get a pegged gauge at cold(60psi gauge), 40 hot and at idle, and 55 hot and 2000rpm

Dennis

 

[Hookin1]

I run rottella 15w-40,

cold at idle......75psi
warm at idle....25psi
at speed.....60psi

 

[ida34]

My deuce also is painted under the hood with 15W40. The oil looked good on pickup from DRMO so I have not changed it yet but will change with with rotella in the next month or so. With the 15W40 I get about 50 psi on start up and it stays in that range but does drop a little on idle after it has warmed up.

 

[clinto]

Mine has 15w/40 painted on it as well.

 

[houdel]

I run Rotellla T 15W40. Cold start is about 60+ Psi, maintains 45-60 PSI at road speed, drops to 30-45 PSI at hot idle. I'm happy with what readings I get. Remember, you are running basically 15 weight oil, it just maintains its visocosity at operating temperature to to equal 40 weight oil at normal operating temperatures.

 

[AMGeneral]

I rebuilt my 465-1C 4 years ago and have used Shell Rotella 15 w40 form the first start.With a 120 psi sender and guage,verified with mechanical guage.

startup=120 psi
warm idle=30 psi
operating temp,2100 rpm=75-90 psi

the oil pressure regulator is working and I have no oil leaks as yet.

 

[JAsher45]

I have built many of these engines in the last couple of years in my GS Maint company. I have seen them when the oil pump fails and even worse, which when they get to me they get rebuilt. one of the reasons the oil pressure is so high at cold start up is the way that the oil flows through the motor.. kinda restrictive passages but this is important for the pressure ensures oil gets from the cam to the cooling nozzles on spray plenty of oil into the cylinder wall. After rebuilding we fill them with 30W and go to the dyno. even with 30W we still have high PSI unitl the engine as had a proper 20 min warm up time before load testing. After dyno runs the filters are changed and 15-40 is put back in. then the engine goes back in the can and out the door.