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Low Oil Pressure

Low Oil Pressure

Postby rglickman [OP] » Jun 06 2010, 2:49am

I have an issue with low oil pressure. The oil pressure gauge was working very erratically for a long time. I finally got around to replacing the oil pressure sensor. Now the truth comes out. When the engine is cold it stays at about 40 psi. When the engine gets warm, the pressure drops. When I am running at speed it stays around 30 psi. At an idle it drops to about 5 psi and the "check gauges” lights come on. My guesses are either that I have a bad oil pump or worn bearings. It is not smoking or knocking. I am running 5W 30. I am going to switch to 10W-30. >>

Need help quick! Thanks in advance for the assistance.
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Re: Low Oil Pressure

Postby duane4238 » Jun 06 2010, 2:29pm

I had the same problem in a Jeep CJ7 I use to have. After warmup, I'd have between 0 and 5 psi oil pressure. To bring things up a bit, I ran 10w40 synthetic and put in 2 to 3 bottles of STP. It worked and brought the pressure up to where I was comfortable. I know a lot of guys think the STP is snakeoil, but we used it for years in our stock car engine and never had one oil related problem. Give it a try.
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Re: Low Oil Pressure

Postby rglickman [OP] » Jun 06 2010, 11:23pm

Thanks,

I switched over today to 10W-30 and actualy had the same thought and put in 1 bottle of STP. I am going to see how that goes. I am a little hesitant about going to the 10W 40 right away. The owners manual is pretty adament about not using it. On the other hand, I change oil every 3000 miles so it really wouldn't have the opportunity to sludge up.
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rglickman
Firing on 1 cylinder [L1]
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Re: Low Oil Pressure

Postby lzn197 » Jun 09 2010, 3:30pm

You didn't say how many miles were on your unit or the age but for now using 10w30 and some stp will help. Have you recently changed a camshaft on this engine and maybe nicked a bearing or changed a valve lifter? In the old days we just put in straight 30w oil in the warm weather and it helped an old engine through many more miles. The only problem with 10w40 is it is made from cheaper oil stock and not as durable as 10w30.
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Re: Low Oil Pressure

Postby Alaskajim » Apr 27 2017, 3:30pm

My 2012 5.3L Silverado with 130k had the exact same issue described on this thread. This is what happened to me and how it was resolved. I got the low oil pressure signal while at highway speed, stopped, checked oil(Full), no engine clanking so I carefully limped it home, stopping several times when the pressure returned to zero. It would jump to normal after stopping for a while. I could get about 4 miles out of it. I changed the oil pressure sender and screen at home. (Its hard to get at, but it can be done easily with a proper set of tools including a oil pressure socket) Ran fine for about a week, then the low oil pressure returned and worse than ever. I foolishly took it to a dealer to have the 'experts' check it out. They called me back later. They had attached a mechanical gauge at the top of the engine and also at the oil filter. They confirmed that the oil pressure at the top of the engine was sliding to zero, but the bottom gauge was normal. They said "we're not sure, but some sort of pressed fitting rotated in your engine and YOU NEED A NEW ENGINE". I luckily called BS on that and told them I wanted to know what "pressed fitting rotated". They couldn't tell me even after I talked to the GM district manager. It all sounded fishy so I picked the truck up and drove it home. Had no problem with the oil pressure in about 20 miles. I started talking and asking around using the internet a lot. I got some things to try. This is what has cured the problem for me:
- I flushed the engine with a 5 minute crankcase flush, I think it was called 'KW 5 minute flush'
- Full oil change using Mobil 1 full-synthetic 5W-30
- A Mobil 1 oil filter, a M1-212. This is a larger filter than is specified. The advice to use a larger filter came directly from a GM technical bulletin.
I have had no problems since this was done about 2000 miles ago. I believe the problem is solved.
An interesting point is that I had no more problems after picking up the truck at the dealer. When I arrived home, I noticed that they had replaced my Fram oil filter with a larger ACDelco filter, A PF63E. I believe the low oil pressure issue is related to the size/capacity of the oil filter. Don't ask me how, but it is my understanding that GM recommends a larger oil filter in these vehicles now. Also, I was using Valvolene Max-Life 5W-30 synthetic blend oil. I don't believe this is an approved "Dexos -1" oil anymore, it was when I started using it, but it is not anymore. I am switching to Mobil 1 full synthetic.
Another small interesting piece of information is that before all this my fuel mileage was dropping from about 16.5 mpg to 15.2 mpg's. After all this fiasco, and changing the TRANSMISSION FLUID, my mileage instantly went back up to 16.5mpg's and is still climbing! The AFM switches to V4 mode much more often.
So here is my advice if you are experiencing low oil pressure: Replace oil sending unit and screen, Flush, change to full synthetic oil and most importantly, use a PF-63E oil filter or equivalent.
I hope this post is of some help.
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