Question for those with a Duramax

[morepwr]

Does your oil pressure gauge seem accurate to you? I recently bought a 2004 GMC with the Duramax and it was very well maintaned and runs excellent. The truck has Amsoil 15W-40 in it and has been changed at every 10K miles and was recently changed just before I bought it. The truck has 111K miles on it.

The gauge is well over 60PSI at idle when cold but once it is warm it just seems to go lower and lower. The gauge goes to 120PSI so when it gets to the low side of the gauge it is still reading about 20-25PSI at idle. It jumps right back up as soon as you give it some throttle but the low idle pressure makes me nervous and was wondering if any of you with a Duramax have seen the same thing on your gauge. The engine runs great and makes no noises to indicate poor oiling at idle but I am curious if this the norm with these trucks?

 

[Stewart Fan]

My 2011 is about the same.

 

[GhostFlame]

Sounds like a nice truck. I had 1982 chevy 1 ton extended van. It had an oil pr gauge and it was all over like yours. Drove me crazy, the dealers mechanic said to ignore it and just keep maintaining the oci. Never had an engine related issue in over 120k miles.

 

[morepwr]

Looking around on some diesel forums I have found out that this is a pretty common thing. It makes me feel a little better about it but it is still odd to watch that gauge go all over like it does.

 

[Jim Allen]

Pressure is simply resistance to flow. That 15W40 doesn't like to flow when cold, versus a lighter oil, so the pressure is high. The oil warms up, flows better and pressure drops. Very normal with all engines.

Many modern vehicles have dampened gauges that don't move much or are essentially an idiot light with a needle... in other words, they show only "normal" or "bad" but nothing inbetween. Your DMax evidently has a "real" gauge that shows actual oil pressure. And that's a good thing! Be happy.

 

[SteveSRT8]

Originally Posted By: morepwr
Does your oil pressure gauge seem accurate to you? I recently bought a 2004 GMC with the Duramax and it was very well maintaned and runs excellent. The truck has Amsoil 15W-40 in it and has been changed at every 10K miles and was recently changed just before I bought it. The truck has 111K miles on it.

The gauge is well over 60PSI at idle when cold but once it is warm it just seems to go lower and lower. The gauge goes to 120PSI so when it gets to the low side of the gauge it is still reading about 20-25PSI at idle. It jumps right back up as soon as you give it some throttle but the low idle pressure makes me nervous and was wondering if any of you with a Duramax have seen the same thing on your gauge. The engine runs great and makes no noises to indicate poor oiling at idle but I am curious if this the norm with these trucks?


I have an 09 2500 HD Dmax, and it is very similar to yours. No worries, change it by the OLM and it'll run nearly forever!