My oil pressure is acting strange. I think the sending unit might be the problem, but don't know for sure. My question to the rest of you is what is the minimum safe oil pressure you can run day in and day out? I have a dual remote bypass that seems to drop my pressure and when I changed to Delvac1 it dropped again. When it was sitting at 30 when warm at idle, I didn't worry. Now I'm seeing it drop below 25 on occation.


Options have considered are:


1. Do nothing as I run full synthetic and a dual remote bypass.


2. Change back to a standard oil filter and stay with Delvac1.


3. Change back to a 15W-40 synthetic instead of the 5W-40 Delvac1 and keep the bypass.


Your opinions on the best option and what a minimum safe oil pressure is would be appreciated.


Chris

From what I remember from school I think the min is 2psi for every 100rpm for an internal combustion engine.


So 600 rpm = 12 psi


But maybe one of the tech's know's exactly what the Duramax min is from the shop manual.


I see your from Texas so I would imagine it's warm there and with warmer weather comes lower oil pressure because the oil runs warmer and thins out more. The 15 and 5 weight part of the oil is the Winter rating the 40 is the summer rating so they Should run the same in the summer since there both rated at 40 but you can try one oil change with the 15w40 and see if it helps any.


Also with a dual bypass kit I would imagine it Could steal some of your engine oil pressure to force the oil through the 2 extra filters. The oil pump can only put out so much volume and if you add extra filters it is sending extra volume there and less to the engine . And with lower volume you have lower pressure.


But maybe the oil pump is big enough to keep up with it all.


And the best way to check your oil pressure is with a Good mechanical guage. Like you said the sending unit could be acting up. I dont think the sending unit's are expensive so you can try a new one for piece of mind.


My .02 Diesel Dragon http://www.dieselplace.com/forum/smileys/Cool.gif

My LLY once warm idles at just under 30 with 15-40 mobil 1300, 2500 miles and it has done this since day one--about two weeks old. Don't woory it's under warranty! LOL!

Mine hit 14psi on delvac while hot, I never used it again. The whole 15-40 thing is a big lie. Dump in 40 wt racing oil and watch the oil pressure go to the top. 15-40 never gets to 40 wt.Edited by: problemchild

Chris,


I second Diesel Dragon's suggestion to hook up a mechanical gauge and verify what the “real” pressure is when your OEM gauge is reading low. One place to temporarily add the gauge is the 3/8 NPT port (http://community.webshots.com/photo/65003591/65005642hlJEYv) on the bottom of the full flow oil filter adapter. I used this port as the feed for my oilguard bypass filter. Before installing the bypass I hooked up a mechanical gauge (from walmart) to this port using a 3/8 to 1/8 adapter. In my case I found the pressure tracked the OEM gauge. One thing to note if you do remove this port is that it’s HARD to get loose. The plug appears to have red locktite on it but it will come out (I had the engine hot when removing mine). I’m also running Delvac-1 and my pressure is rock solid even when hot. For example I was recently driving in 50-60deg weather with my cloud rider cold front (http://community.webshots.com/photo/63497470/103356739mpWojf) still on. Coolant temps were 205-210 on hills and the oil pressure was still 28psi at idle and 60-65 psi at 2k rpm


http://www.dieselplace.com/forum/smileys/Geek.gif

Thanks guys. I might get a gauge to verify the sender. Most of the time, I see ~27-28 psi when warm at idle. Since most are seeing somewhere in that area, I feel like I'm should be in okay shape. I might also throw a single full flow filter at it depending what the gauge check says.

The first number is the base weight of the oil. So in the example of 5W-40 you are running 5 weight oil that will lubracate like 40 weight oil, this is a winter or cold weather oil. 15W - 40 is 15 base weight oil that will lubracate like 40 weight, this is a summer or warm weather oil. Since you live in Texas you should be running the 15w - 40 oil as we do in southern calif. The reason the Manufacture recommends 5w - 40 is they run that oil during emissions testing and they are required to give whatever oil they ran during the testing as the recommend oil by uncle sam. The thinner oil allows less drag and helps emissions during the test cycle.