Oil Pressure Changes during an OCI

[The Critic]

On my 5.7 HEMI, a fresh fill of 5W20 synthetic (M1 or PP) and OE Mopar filter results in a hot idle oil pressure of 30 psi.

After 3K miles, it drops to 27 psi.

Is this purely due to the oil's viscosity loss?

 

[Astro14]

That would be my guess. 10% seems like a reasonable loss for a regular oil, and I mean no offense by that term, even though they’re synthetic. Most of my cars don’t have an oil pressure gauge (sadly, only two do) so, I can’t validate your observation but your guess makes sense.

 

[Trav]

Yes that is what it is. 3psi is nothing to worry about.

 

[The Critic]

Yes that is what it is. 3psi is nothing to worry about.

Agreed, and I'm sure 27 psi is well within spec.

Though... with the oiling issues that HEMI engines can have, it does make me wonder if keeping it around 30 psi can help improve longevity.

 

[JohnnyJohnson]

On my 5.7 HEMI, a fresh fill of 5W20 synthetic (M1 or PP) and OE Mopar filter results in a hot idle oil pressure of 30 psi.

After 3K miles, it drops to 27 psi.

Is this purely due to the oil's viscosity loss?

A UOA would perhaps give you a clue? What is your viscosity and what is your fuel dilution?

 

[Jetronic]

On my 5.7 HEMI, a fresh fill of 5W20 synthetic (M1 or PP) and OE Mopar filter results in a hot idle oil pressure of 30 psi.

After 3K miles, it drops to 27 psi.

Is this purely due to the oil's viscosity loss?

and backpressure from the oil filter possibly... no strike that, the maximum pressure would drop

 

[The Critic]

A UOA would perhaps give you a clue? What is your viscosity and what is your fuel dilution?

I have never done one on this truck. Maybe I should.

 

[Sam_Julier]

That is consistent with my experience with the 240 wagon. 2-3 psi drop running 5W40 full syn.

 

[SteveG4]

Nice thread. Great question with sensible answers. Learned something today.

 

[The Critic]

I found a prepaid Wix UOA kit in my arsenal. I will drain the oil and send in a sample.

 

[JavierH19]

about normal with any vehicle. oil shears a tiny bit. If it concerns you you can use a thicker grade. I believe you have to abide by the chryler 6395 which lets you go up a grade but i don't think it's warranted.

 

[tiger862]

At 10 psi per 1000 rpms you are OK. As a former technician I have heard it is better to have 20 psi at idle than 40 psi with reason being lower pressure keeps oil on bearings longer.

 

[JTK]

My 2019 Ram 1500 hemi classic indicates about 50psig+ on cold starts and 38-42psig at idle at normal op temps.

I say indicates, because I'm going by the digital readout on the dash. I have no idea how this would compare to a scan tool indication.

I do notice a 1-2psig drop once the oil gets some miles on it. I change it at at 5000mi interval. The OLM is around 50% life remaining at that point.

I also run only 5w30 as opposed to the recommended 5w20 since I've owned the truck at a year old with 15K miles on it. I'm just shy of 46K miles currently

I used to run the standard supertech synthetic 5w30. For the past year or so I've been using the fancy "20K mile" supertech synthetic 5w30.

Still adding either a bottle of lubegard bio tech or LM MoS2, or nothing. I rotate it that way until my stock of the two run out and that will bit it for that.

 

[OVERKILL]

What's your oil temperature? I saw 27PSI on my M1 EP 0w-20, but that was with an oil temp of 104C (~220F). It usually sits below 100C and is in the mid to low 30's.

 

[The Critic]

What's your oil temperature? I saw 27PSI on my M1 EP 0w-20, but that was with an oil temp of 104C (~220F). It usually sits below 100C and is in the mid to low 30's.

210-220F

 

[OVERKILL]

210-220F

I'd say it's pretty normal then. My temp isn't normally that high, but of course, I live in Canada. I'll get my wife to check it before she turns the truck off today when she gets home from work though and update you.

 

[OVERKILL]

OK, so my wife's drive home didn't get the oil up to temp (that's 160F):

 

[JTK]

Here's a pic of mine from today after a ~40 mile run w/ just under 5K miles on the oil.

 

[BornSlippy]

In my 2019 DT Hemi, I ran Rotella Gas Truck 5w-20 for the first 18K KM. Hot idle oil pressure was always around 27-28 psi. Last change I put in QSFS 5w-20 and hot idle pressure is around 30 psi, I have about 3.5K KM on this OCI.