low oil pressure

[TallyMax]

I had an experience today where after a run at lunch time the oil pressure yielded less than 30 psi at an idle. I let her idle after I had come to a park to cool down. When I revved the engine up the pressure goes back up to where it should be, it just seems a bit low and lower than it has in the past. Usually around 40 is where it's at when warmed up and at an idle. It was 95 degrees and I had just done some stop and go. I'm using a premium 5w30 HD diesel synthetic. I'm just wondering if that's too thin down here or if 30 psi is fine and the oil's doing what it's supposed to. I guess I've still got the "old school" quirks where the more the oil pressure the better and the thicker the oil the better. Anybody else's pressure that low at idle?

[6600 Duramax]

Hey TallyMax

I also experince pressure a tad below 40 psi when it is warm and have been driving for a while. I am also using 5W30 HD Synthetic Amsoil

I wondered the same thing just never asked.

[CSDMAX]

TallyMax,

There are many discussions on this BB about which oil to use.
Manual reccomends:
15W-40 for 0 deg and above.
5W-40 for below 0 deg.
Greg Landuyt will tell you (Landuytg)
"Amsoil Series 3000 5W-30 is the best oil that you can put in the Duramax. You will have better protection with this oil than you will with any 40 weight. Many F*** and D**** owners using this very oil in ALL climates year around."
Don

[PEANUTGRWR]

HAVE ANY OF YOU EXPERIENCED THE OIL PRESSURE HAVING TO WAIT SEVERAL SECONDS BEFORE IT COMES UP OFF OF 0 WHEN YOU START YOUR TRUCK. MINE DOES THIS QUITE OFTEN IT DOESNT MATTER IF ITS SAT FOR 5 MINUTES OR 24 HRS JUST SOMETIMES TAKES TAKES A WHILE FOR IT TO PRESSURE UP. IT ACTS LIKE THE OIL HAS JUST BEEN CHANGED AND THE FILTER ECT IS EMPTY. I JUST WONDER IF THERE IS SOME KIND OF CHECK VALVE INTERNALLY IN THE ENGINE THAT IS LEAKING OFF.

[JLee]

Peanutgrwr - I see the exact same thing with my truck. Like you said, it doesn't seem to matter if its hot or cold, sometimes it just take several seconds to move off zero. Kinda unnerving.

[csimo]

Check and make sure you don't have a crankcase full of diesel fuel. Several people have had failed injectors that pumped fuel into the crankcase. They all reported low oil pressure as the first symptom.

[FirstDiesel]

How about the oil filter?? Those of you seeing no pressure at startup, what brand oil filter are you using?? Remember these filters sit sideways and probably drain most of the oil out when they are sitting. In my sportscars we see a big difference in oil pressure based on the brand of filter. My experience has been Fram is a questionable unit. Purolators have been good.

[Dinkie Diesel]

Forgive me, but why would anyone put 5w-30 in their diesel this time of the year. I know it's a lubricant and better than nothing. If it's down in the 30's I could understand. At speed it would seem to me it's keeping a lot of oil suspended before draining back to the pan. Probably not going to starve the pump with 8 or 9 qts in there but please enlighten me if I missing something.

I have heard that diesels need a cushion of oil to accommodate the quick nature of it's combustion. Is this a fairy tale?

[thechevyhdman]

I have noticed nothing less than 40psi recently and the temps here have been around 90-95. I run Citgo citguard 500 15-40, And also run the delco stock oil filter. I have also noticed a long time pause on initial start up for pressure to build. One time it took so long my check guages light came on super quick, at least I assume thats what idiot light came on. Disappeared as fast as it came on. But once I even touch the gas pedal it goes up well over 60 psi. I just changed the oil 2 weeks ago, And didnt notice any fuel in my oil at all. My trucks a 2002 Dmax Alli, with about 16,000 on her. Its still well above the 20 psi mark my 6.5 puts out at idle when its warm, But miss the days when my Dmax put out nothing less than 75 psi ever. I have noticed that my truck seems sluugish, and not really wanting to rev up lately but I have been trailering with it, It doesnt realy go below 1500 rpms but sometimes feels like It should have a bit more sack to it. Im only towing a few lawn mowers and other equipment weighing no more than 3500-4000 #s. If it is a bad injector or whatever, what other symptoms should I look for?

[FirstDiesel]

Have you checked the airfilter??

[01_Duramax_Dually]

I use Redline synthetic 15W -40. I use it year round but I live in California and the temp never drops below 40's, routinely 50's. Right now the temps are hovering in the low 90's and this past weekend in Fresno and Yosemite we saw temps of 100-104. I was towing the boat up some pretty brutal grades off Road 200(8% grade for 3 miles). Oil pressure was like it has been from purchase. My oil pressure is always 40+ at idle then runs up towards 70+ when driving at speed.

As for the filter laying sideways, actually it lays at about a 30 degree angle downwards. The oil filter does not drain empty. Matter of fact, with the drain back feature of the filters, it should remain full.

The start up pressure you see in the gauge is not indictive of what is really happening. Remember you are dealing with an electrical sending unit not a copper tube that is piped directly into the oiling system. What you see is very common. Anymore than a couple of seconds might make me concerned and want to add a different gauge just to make sure all is well.

Again, at oil change. I highly recommend Pre filling your filter. It does not spill out when you screw it on. It better not. That means the filter you are using does not have the drain back bladder in it. You should be able to fill the filter completely, put your thumb over the hole where it threads into the engine, turn it over and have very little, if any, oil come out at all.

Carry On....

[DURA-MAX3]

I run delo 400 15/40 and have no problems at all with oil pressure or using oil as i have heard some reporting they are doing. i ran delo 400 in my caterpillar engines with very good results and will continue to use it in my d-max...