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need advice on oil pressure

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So, I have a few questions regarding the occasional low oil pressure on the 5.3L.  I understand that the oil pressure screen can be the issue, I also know that the pickup tube O-ring can be the problem.

Here is my situation:

Last fall I was at the end of an oil change (was over by maybe 100 miles) and we went for one last camp trip.  It was a 1.5-hour journey.  Towing the trailer PSI was maybe 35, when I would reach towns, and stop at lights the psi would drop to 19-20 PSI.  Then we got stuck in stop and go traffic and the PSI would drop to almost 0 and the warning came on.   I pulled over, shut down, checked oil, all good.  waiting maybe 10 minutes, fired up the truck and PSI was 40.   This scenario happened 2 more times (about 30 minutes apart each) until we reached our destination.   The following morning, I drove it into town and had an oil change.  Our trip home was ok – no issues.


Talked to my mechanic and he said probably no issue – maybe I had some debris or sludge plugging the screen on the oil pressure sensor.


I had no issues all winter.   I just changed my oil using Mobil 1 full synthetic and a Mobil 1 filter.

Cold Start I get 45 psi, at operating temp under load I get 40 – at idle (at a light) 25 psi.


I am gun shy about pulling the trailer next month.  Am I overly concerned?

Questions for answering:

1.      If the O-ring is bad – wouldn’t I have issues ALL the time?

2.      Should I insist on having the pressure sensor replaced along with the screen?

3.      Can the oil pressure sensor give a false warning?  My buddies came on when he pulled his trailer and he drove it that way for another 1.5 hours at highway speeds and has had no issues with engine performance.


I bought a new pressure gauge and oil temp gauge and pods from Glow-Shift, and I am going to install them as a secondary way to measure oil pressure and temp.  I am doing it this weekend.


Sorry to bring up a topic beat to death – but I just don’t get why this happens only “sometimes” and why shutting the truck off, waiting, and restarting seems to fix the issue for 30 minutes (in my experience)

Truck has oil changes at the shop as recommended.  All maintenance has been consistent and up to date.


Appreciate any insight and wisdom anyone can offer.

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I've had similar issue once, also pulling a  trailer, boat trailer.  2011 Sierra, 150k miles.  Put in new oil sensor.  Helped some....30psi at highway speed, 25psi idling in gear.  Some change, but not a lot.  At the recommendation of some on here I changed oil and this time did it myself.  I've always used the dealer oil and their service (dexos).  I put in Mobil 1 and the high end Fram filter (for synthetic oil).  The issue went away.  Regular highway speed 40 psi.  Idling in gear, 30psi.  Due to my age I went back to letting the dealer change oil.  Most of the time I'm running 39-40psi at highway speed, 28-30 idling in gear.  Yesterday pulling the trailer I noticed 38psi at 60mph and 22psi at idling.  Oil change was less than 1k miles ago.  My independent mechanic said not to worry over this, GM specs were that I was safe to 6psi, but if it dropped down to under 20psi let him know.  So, I've done just that.  So, I'll be interested to see the replies you get.

Edited by Jworks
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That sounds like the pick-up screen may have been partially obstructed and the oil change cleared it. What is your oil change interval? Could also have been the filter as J suggested

Edited by richard wysong
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My 12 has 60psi cold start, over 40 warm with 74K miles. If it bothers you, fix it. Others wise I think it's fine.

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if memory serves, it was an AC Delco filter last fall during the pull.  and I am sure bulk synthetic oil that's 5w-30.  I change my oil at the sticker mileage or when the display says so, whatever comes first.  i think every 5k.

when I was camping and had the oil change, I am not sure on the filter - other than it was a white filter, and on a Saturday morning in the middle of nowhere, i took what I could get.   we did a flush at that time as well.  I am just gun shy, I guess.  

the question remains, listen to the chimes? and shut off engine?  or keep going like my buddy?   I have 119k on this engine - purrs like a kitten and never had any issues until last fall.  had this truck since 60k miles.  PSI dropping below 20 is not the norm for my truck.  My mechanic is honest - too honest - he doesn't want me to waste money on the pressure switch/screen change because he doesn't see an issue.  and I don't want to tackle it.

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Ok I will go out on a limb here. Many people have dealers do oil changes, I do my own because I get to pick the products.

At the very least if I wasn't doing my own oil changes I would find a shop that lets me bring the products of my choice.


White oil filters are most likely fleet filters which is what most oil lube shops use, they are the cheapest filter. I used to use them buying them by the dozen. Never had an issue but I do shorter OCI's. 


I believe the bulk oil dealers or lube shops use is the lowest quality they can get by with, same as fleet filters. Poorer quality oil and cheap filters combined with longer OCI's isn't good. Plugs things up just like a poor diet plugs up arteries.


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I just did an oil change 2 weeks ago - Mobil-1 full synthetic and mobil-1 filter.  i plan on doing my own changes on my truck from now on.  My mechanic recommends AC Delco - and that's all he uses.  Not sure on the oil he uses - I assume a 55 drum of bulk.


back to the o-ring issue for some - if the o-ring was the issue - wouldnt they have horrible oil pressure ALL the time?

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I think there is a test for the o'rings by overfilling the crankcase, this would submerge the o'rings I think. Google it. 

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When the pressure went to 0 did the motor get noisy? If not it is probably oil sensor or clogged screen. The o-ring if it was bad would do it all the time.

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