Have you checked the filter for leaks? If it's not leaking I'd change it. May have a bad drain back valve.

 

^^^^ this. And use a good quality filter; AC, Napa Gold, Wix, Mobil 1, etc. It can make a big difference.

 

Not sure if this might help any in diagnosing problem:

 

Changed the oil filter, same thing still low oil pressure.

 

Did you use a different oil this time when the problem started?

 

Running 5W30 full Synthetic? Not interested in the brand just the API weight. Some are better than others but I'm not interested in starting a holy war. I tend to gravitate toward the higher zinc content oils. Get educated and look up the VOA sheets on BITOG then make your own mind up.
Oil was changed in the last 5K or so. Is it still full on the stick?
WIX is a top shelf oil filter. NAPA Gold is WIX. Try an AC Delco filter with some different oil and see if that makes it happier.

Replace the oil pressure sensor with a new GM or AC Delco unit. If it's an AFM Displacement on Demand engine replace the lifter filter screen under the oil pressure sensor.

If all of the above are correct and happy then it's time to look at the oil pump and oil pump pickup O-ring. My 6.0 was running 30PSI at startup and 25 hot idle and it was ticking initially when it was cold and sometimes on hot starts. Kinda like an old fashioned flat tappet hydraulic lifter set with cruddy oil.
I installed a Melling stock pressure and stock volume oil pump with a new pickup tube and the add-on 2 bolt pickup tube clamp. Pressure is now 45-50psi at startup and 40 PSI at hot idle. No ticking.
High volume LS oil pumps can suck the pan dry and high pressure pumps are an unnecessary expense for a daily driver engine.

 

I have not stuck to 1 oil brand. I used supertech 5w-30 conventional for about 15,000 miles before this problem. Then i put in vavoline 5w-30 conventional, then problem started. Oil is clean and full. Sensor is new and also the screen, changed those out about 20,000 miles ago. So it looks like im looking at an oil pump or pickup o-ring?

 

I would try a new lifter filter. The oil change might've kicked some crud loose and somewhat blocked up the screen. They're $5...

 

THE screen under the oil pressure sensor? If so. ill check it out tomorrow.

 

Screen is squeaky clean. Just checked it.

 

Is the ticking actual ticking or more like a rattle? And does it go away after it warms up? If it does, then it might just be piston slap (doesn't explain the low oil though). Otherwise if it continues it may be a collapsed lifter.
You may also want to try a synthetic oil too. I know that most new vehicles recommend synthetic. I don't know if this would be an immediate issue, but like what someone mentioned earlier, you may have also knocked something loose that's causing the low oil pressure. Also I'm not sure how conventional oil affects the collapsable lifters if this truck has AFM.

Maybe also put a mechanical gauge on it too one of the days (at startup in the morning) and see what it says and compare it to the truck's gauge.

 

Switch to 10w40 synthetic oil and see what the pressure is.

 

Oil pump and p/u should be next on your R%R list. Change em out and do an oil change.

 

Ok so today i just decided to run a diagnostics on the truck, and 5 codes popped up. P0573, p01175, p02270, p0521, p0522. Sh%$! i guess maybe i am in more trouble then what i thought. And there is no check engine light, which is strange to me. Lets stick with the oil problem codes for now. Drove the truck for about 90 miles today, started it about 25 times, and same thing. Low oil pressure in the morning at idle, but ounce warms up it will idle fine. Truck seems to run smooth otherwise. I still think i might swap out the pump and o ring. But wanted to get your opinions first.

 

I am having a similar problem with my 08 silverado 215K miles. About mid August my oil pressure dropped to 0 for the first time then popped right back up to normal. I thought this was weird and possibly related to the oil pressure sensor because I had replaced it early this year around January. At that time the oil pressure was 0 all the time, replacing the sensor fixed it. I did not replace the screen filter behind the oil pressure sensor though. Fast forward back to present...my oil pressure started fluctuating more frequently. The needle on the gauge would drop and go up, then go to 0 and stay there for several seconds to a minute, then come back up. It was so sporadic I couldn't tell if these were actual readings or a flakey connection. One time while I was parked the pressure went to 0 so i got out and wiggled the wire harness to see if the wiring was bad. That did not effect it. My gut told me there was no way the actual pressure was 0 or I would start to hear lifter ticking or even worse, but I do not want to blow my engine either.

So I started digging a little more and learned about the pick up tube o-ring issue. This sounded like the issue I was having, when i'm parked facing down hill it would never fail. This made sense because the oil runs to the front of the engine and the o-ring is submerged in the oil at this point. Last night I dropped the front axle and the oil pan, and replaced the o-ring. I took it for a test drive and thought it was fixed. The oil pressure was more responsive and never dipped below 30. Then today it went to 0 on me again and here I am looking for a solution. I attached the old and new o-ring photo for anyone to see who was interested.

I need to collect more data. I need to know what the actual oil pressure is when the gauge say 0. I am going to try to install a mechanical gauge somewhere on the block and compare it to the dash gauge next time it goes to 0. This will tell me if it is electrical or mechanical. If its electrical its not as critical but at least i will know it is not inside the engine.

 

When I did my oil pump and pickup tube I used a girdle on the pickup tube collar to utilize both bolt holes.
Whether this makes a huge difference or not is an open question.
I didn't like the fact that the pickup tube could cant to one side when I was installing the new pickup tube and screen.
Once the bolts on the tube were in place it stayed put but I still didn't like it.

I used the ICT part in this picture but there are a lot of them out there.

https://www.amazon.com/Billet-Pickup-Gi ... B0784JPH59

 

I didn't like that there was one bolt either. That's is a good idea.

I am trying to find a way to install a mechanical oil pressure gauge. I saw that there is a cover plate on the side of the oil pan above the oil filter. I believe I can tap into this but I'm not sure what is underneath this cover. Fires anyone have any idea or know out another easy way to install an oil pressure gauge?

I was planning on using the $28 harbor freight gauge, just not sure where to tap into.

 

The bypass valve has a reputation for failing on some LS engines but I believe it's more than just at startup.
I think that was one of the issues on my truck.
New oil pump has a new bypass valve so that was that.

 

I bought an adapter plate off amazon with a 1/4" NPT hole drilled in it for about $14. It bolts to the oil cooler ports on the side of the oil pan directly above the oil filter. I went to harbor freight and bought their oil pressure test kit which came with a gauge, 66" hose and all the fittings i needed to mount it to the adapter plate. It cost about $28 but I had 20% off coupon. I ran the hose up inside the engine bay on the driver side where there is a blank spot for a second battery and zip tied it down so the hose is not flopping around or getting too close to the exhaust. With the gauge installed i drove around until my oil pressure went to 0 and got out to read the oil pressure gauge. I still had oil pressure. This tole me that it was something electrical with the pressure sensor or harness etc. The easiest thing to do was change the oil pressure sensor which I had already change In February because it failed hard over. Well when i wen to remove it I broke the connector off the body and I think I found the problem. It looked like there was barely any solder between the connector and the PWB inside the sensor. The engine heat was probably causing an intermittent connection causing the oil pressure reading to fluctuate. I went to the junk yard and pulled 4 sensors and tried a new one and so far it has been working fine. It is pretty sad that i spent $40 on a brand new AC Delco part and only got 6 months out of it. I hope this is the last of the oil pressure saga. I didn't think i would have to replace the sensor twice but I did, so maybe if you are having trouble with your oil pressure this will help you. You might have a faulty sensor even though you might have just replaced it.

 

Good info. Thanks for posting. I'm glad you got it resolved.

 

Took truck to mechanic. New oil pump and gaskets, it now runs like a top! Oil pressure problem solved.

 

Weird. I got 215k on my truck and the oil pump is still running good.

 

Nice. This is a great info thread.

My first thought was that oil is not flowing (duh) but there could be several causes.

I've seen that 'low oil pressure, turn off engine' pop twice but it was -25 F in the early AM and everything was sludge. It went away in 10 seconds after the pump was able to get it up out of the pan.

The other odd thing I just noticed was better cold start pressure after replacing the cooler lines. I mean it goes slightly above 40 psi now and seems to stay there longer. Maybe one was breathing a bit on start up?

 

Weird. I got 215k on my truck and the oil pump is still running good.

You just jinxed a bunch of us, brah!!

 

Weird. I got 215k on my truck and the oil pump is still running good.

You just jinxed a bunch of us, brah!!

Haha...Sorry in advance.

I just don't understand how these pumps fail. The gerotor style pump should not wear much at all, especially with a cavity full of oil for lubrication all around it.