Drop in oil pressure

[clandr1]

Hey guys, up until about a year ago my truck would hold a minimum of 40 psi oil pressure at idle no matter whether the motor was cold, or warm. After a 6 hour each way trip in March of 2021, I noticed my "hot" oil pressure was around 30 psi. As this summer has set in, I've noticed the hot idle oil pressure dropping to around 25 psi as of late after 2+ hour road trips, but when I'm driving, pressure is still at or above 40, depending on throttle position and load.

Background: I have used Mobil 1 High Mileage 5w30 full synthetic religiously since 75k miles, always change the oil when the computer tells me, and I've always used quality oil filters. I have also sent my oil off to Blackstone half a dozen times or so, and nothing has been concerning. The most recent analysis was May 2021 at 226k miles (approx. 14k miles ago) and all looked good, nothing outside of tolerance when compared to my historical oil reports dating back to 133k miles.

I should mention that I replaced the pickup tube O-ring in late 2017 around 170k miles after the motor developed a slight ticking noise (the O-ring was replaced immediately, and I do not believe I sustained any damage from the low oil pressure).

I figure the most likely options for me are as follows:
1. Keep driving it and not worry about it until it goes below an arbitrary level (20 psi?)
2. Use thicker oil (if you think this is the right choice, please tell me what weight you think would be best - I'm leaning towards 10w40 if I make a change here)
3. Proactively repair/replace motor internals (please be specific, and keep in mind this is not something I would tackle personally and would likely have to pay a shop to do the work which terrifies me)


I would appreciate any constructive feedback or opinions. Thank you.

 

[Matahoe]

I only see 30 psi at idle when stopped at an intersection for instance. This would be hot ambient temps as well. Roughly 40 -60 psi any other time driving. Is your oil pressure needle moving relative to throttle input/load?

 

[Matahoe]

You may be suffering from a slight filter screen blockage. You can remove the oil pressure switch and take it out spray some carb cleaner on it in reverse flow direction. May want to replace pressure switch which is cheap insurance at your mileage.

If your up to it I would then try an oil flush. Throw in a couple quarts of kerosene or K&W Gunk engine flush. It has similar ingredients but more pricey.

 

[MassHoe04]

There is also some chance that your pressure is not actually a problem...

Do you know for sure, that the pressure sending unit functioning properly and that the pressure gauge in the cluster is indicating the correct pressure based on voltage received from the sending unit?

See if you can get an oil pressure test gauge on there and check cold and hot pressures with the external test gauge.
I'd hate to see you tearing things apart, if it turns out there is something stupid in the electronic reading and display of information.

 

[Joseph Garcia]

20-25 psi at hot oil idle is normal. As long as it goes back up to 40+ psi over 2000 rpms.

 

[Skeeter]

I suspect the oil pressure sensor. I bought my used Yukon Denali at 110K and the oil pressure never dropped below 40 psi and cruising at 75 mph 60 psi. Last month the pressure suddenly read 0. Changed the oil pressure sensor and the pressure is back. Now the pressure at idle is 20 psi and cruising 45 psi. I suspect the old sensor was reading high. Change it yourself if you can. I took it to a shop and they charged me $650 as normal procedure is to remove the intake to get to the sensor. There are YouTube videos on how to do it without removing the intake.

 

[Fless]

You may be suffering from a slight filter screen blockage. You can remove the oil pressure switch and take it out spray some carb cleaner on it in reverse flow direction. May want to replace pressure switch which is cheap insurance at your mileage.

If your up to it I would then try an oil flush. Throw in a couple quarts of kerosene or K&W Gunk engine flush. It has similar ingredients but more pricey.

There should not be a filter screen on a non-AFM engine.

 

[Cbncanada]

It could be one or more of several issues. First go to a 10W30 oil and new filter. Have the engine oil system flushed. Run a can of Sea Foam liquid mixed into the oil to do additional cleaning. That would help if you have sludge deposits reducing the oil flow. Other issues could be the front cam bearing is getting worn. This one will affect oil pressure.

 

[Matahoe]

Sea foam really isn't meant to be added to your oil. Just intake and fuel system. SF is primarily a fuel system drier comprised of mostly isopropyl alcohol..nothing else.

 

[MassHoe04]

On my 4.0L 2005 Jeep Rubicon, I kept up with oil changes every 3k miles. It got cleaner with every oil change.

I was hesitant to do any kind of deep clean with solvents or things like Seafoam or the old ATF fluid in the oil trick.
My gut was telling me it might do more harm than good on an old high mileage engine.

I figured it took years for deposits to build up on seals and gaskets. It wasn't leaking a drop on the ground. If I did a hard cleanse, I was afraid the deposits that were helping keep the oil in would not be there anymore and the oil would start spewing out like a faucet. Oil pan gasket and RMS never spilled a drop! I left it that way and just did the frequent oil changes.

Here is what it looked like inside when I did the valve cover gasket replacement... It had 183k when I bought it and it was about 225k here after 3 years.