Why does a UPF48r filter result in more engine oil pressure than a PF48e?

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I have a 2012 Suburban 1500 with the 5.3 LS engine. 171,000 miles, original owner. Started using oil at about 100,000 miles and now uses a quart anywhere between 500 and 2000 miles depending on what I'm doing (faster when towing a heavy trailer through the mountains, slower when less heavily loaded). I've had recurrent p0521 check engine light warnings since June 2020. It is not the sensor or the screen and I've verified pressures with an analog gauge. My engine is likely just decently worn after fairly heavy use.

I just installed a UPF48R filter instead of the default PF48e after seeing the GM TSB recommending this step when a p0521 error persists. I can see pressure is higher with the UPF48r.

But, I'm not understanding what it is about the UPF48r that results in a higher pressure than does the PF48e? Clearly it is some difference due to the filter, as otherwise GM would not recommend using the UPF48r for this case. But how does the UPF48r filter result in the engine operating at a higher oil pressure than does the PF48e?

I'm an engineer and am curious to understand physically how this change helps increase oil pressure. Thank you for your input.
 
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I did find this but cannot verify the credibility:


Thicker gauge metal in canister body as well as much finer filtration rating.
 

russellbailey

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Thanks. It is clearly a much heavier metal body and likely is twice as heavy as the 48e despite being almost the same size.
 
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Is it safe to say the 48R is a direct swap-out for a 48E?. I have an LSA and have long favoured the size of the 48R (and apparent can thickness) over the OEM-Spec 48E.
 

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Doubt the PRV would open with a new filter …
That engine should have room for something bigger and free flowing like the Fram XG10575 …

Think the new pumps came in 2014 …
 

russellbailey

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In case you have not seen the TSB I was referring to.
——
Service Information Home Publications Number Search New Bulletins Bulletin Search Feedback Help
2012 GMC Truck Sierra - 4WD | Cheyenne, Sierra, Silverado VIN C/K Service Manual | Document ID: 4211936
#PIP5276D: SES Lamp P0521 Setting After An Oil Change And Or Low Oil Pressure Indicated On The Instrument Panel - (Jun 8, 2015)
Subject: SES Lamp P0521 Setting After An Oil Change And Or Low Oil Pressure Indicated On The Instrument Panel

Models: 2007-2013 Cadillac CTS-V, Escalade
2007-2013 Chevrolet Avalanche, Camaro SS, Colorado, Corvette, Express, Silverado, Suburban, Tahoe
2007-2013 GMC Canyon, Sierra, Savana, Yukon
with a V8 Engine (RPOs L20, L77, L94, L96, L99, L9H, LC8, LC9, LH9, LMF, LMG, LY6, LZ1)
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern
A concern of a P0521 Setting After an oil change and or low oil pressure indicated on the instrument panel.

Recommendation/Instructions
If you are working on a Gen4 V8 that is setting a DTC P0521 and or low oil pressure indicated on the instrument panel in cold or hot weather and the engine is currently equipped with a PF48E oil filter, replace with a UPF48R oil filter if one is available.

Note: Only use the UPF48R oil filter if theGen4 V8 is setting a DTC P0521.

Warranty Information
For vehicles repaired under warranty use:

Labor Operation
Description
Labor Time
4065530
Oil Filter Replacement
Use Published Labor Operation Time
Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.
 
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Can to describe where you took confirmed the pressure reading? Was it where the pressure sensor usually resides at the back of the block next the the firewall? If that is where you are getting your pressure reading, a free flowing filter would allow less pressure drop across the filter media resulting in a higher pressure at the top of the block. Sound reasonable?
 

russellbailey

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Thank you.

Yes, the pressure reading is at the back of the block next to the firewall - the analog gauge verified that the electronic sensor is reading correctly.

I'm unclear on the oil flow path - I know that sensor location is connected to the oil filter (I blew down the hole with compressed air when replacing the sensor one time and the air exits the filter area) but was not clear on the flow direction or what else ties into that. It sounds like that sensor is measuring the cleaned oil flow that is leaving the filter?
 

ZeeOSix

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Thank you.

Yes, the pressure reading is at the back of the block next to the firewall - the analog gauge verified that the electronic sensor is reading correctly.

I'm unclear on the oil flow path - I know that sensor location is connected to the oil filter (I blew down the hole with compressed air when replacing the sensor one time and the air exits the filter area) but was not clear on the flow direction or what else ties into that. It sounds like that sensor is measuring the cleaned oil flow that is leaving the filter?
Yes, the oil pressure sensor located on the top back area of the block is after the oil filter.

Does this engine have the filter bypass valve in the filter, or in the block like older GM engines?

What were the oil pressure readings you found with the mechanical gauge, and under what conditions?

Maybe the ADBV is leaking on the filter, and allowing air into the galleries above the filter, which could cause a momentary low oil pressure condition that trips the DTC.
 
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I can help a bit. The bypass valve is built into the filter. The ADBV allows flow in the normal pumping direction. It seals when the pump stops so no fluid comes back through the filter, so no, it would not allow air into the system.

And good question. Could you tell us more about the pressures you saw. I’ll scare up a diagram of the LS engine gallery design. Yes, blowing air into the gage hole would reach the filter boss.
 
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Here is a schematic how the oil galleries are set up. The item highest up represents the pressure gage location.

Oiling system LS engine.PNG
 

russellbailey

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Awesome - I never saw less than 20 on the analog gauge with the 48e and oil at 60% life left. But it may have gone momentarily lower.

I can post more details tomorrow. It was an intermittent p0521 - would come on and stay on a 100-400 miles and then clear itself. Oil was normally a little below full when it triggered, but never to the add 1 qt level and typically at 2 dots on the dipstick.

3 of the 4 times p0521 came on was when the engine was under heavy load - pulling a trailer or climbing a very steep grade.

The attached picture is of 60 mph on flat highway with the 48e filter and oil at 60% life and 4 dots on the dipstick.

I don’t have great ones yet with the new filter and fresh oil. But it seems to now idle at about 30 psi where before it idled right at 20, with warm oil.
 

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Cool data. What software are you using? Thirty is pretty normal. Twenty is definitely low. You have the pre-2014 system, so normal highway cruising pressure is 40 psi, slightly higher if you floor it and pass someone at high rpm.
 
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russellbailey

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Using ELM Car Scanner Pro on an iPhone with a VeePeak OBD2 adapter. I mapped that screen to track what seemed like the relevant parameters - it is neat in you can pick how to show each parameter. The graph I’ve got is a 2 minute window but you can pick whatever duration you want there.

A mechanic that I trust and was recommended as very good with the LS engines checked everything and found nothing obviously wrong and concluded it is most likely just a worn engine. It is down on power some but that is only really noticeable when towing at capacity in the mountains.

So, I’m experimenting with the filter recommended in that TSB and seeing if that will improve pressure sufficiently to keep going a while longer with same engine or not. We use this car for long family travel and reliability is critical for that - if I have to replace the engine at some point to do that I will, but I don’t want to do it before needed.

That diagram is really helpful and explains the oil flow well - thanks for that.
 

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ZeeOSix

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I can help a bit. The bypass valve is built into the filter. The ADBV allows flow in the normal pumping direction. It seals when the pump stops so no fluid comes back through the filter, so no, it would not allow air into the system.
It could allow any oil in the galleries above the filter to drain out. If that happens, it might cause erratic oil pressure reading upon start-up until all the empty areas of the oiling system is filled with oil again.
 

ZeeOSix

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Awesome - I never saw less than 20 on the analog gauge with the 48e and oil at 60% life left. But it may have gone momentarily lower.

I can post more details tomorrow. It was an intermittent p0521 - would come on and stay on a 100-400 miles and then clear itself. Oil was normally a little below full when it triggered, but never to the add 1 qt level and typically at 2 dots on the dipstick.

3 of the 4 times p0521 came on was when the engine was under heavy load - pulling a trailer or climbing a very steep grade.

The attached picture is of 60 mph on flat highway with the 48e filter and oil at 60% life and 4 dots on the dipstick.

I don’t have great ones yet with the new filter and fresh oil. But it seems to now idle at about 30 psi where before it idled right at 20, with warm oil.
Is the DTC is triggered off a low oil pressure signal from just the sensor alone? How do you know if the oil sensor isn't going flaky? That was a big issue on the LS6 and LS7 engines on the Vettes. Oil would seep into the guts of the pressure sensor and cause it to flake out and become erratic.
 

russellbailey

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Is the DTC is triggered off a low oil pressure signal from just the sensor alone? How do you know if the oil sensor isn't going flaky? That was a big issue on the LS6 and LS7 engines on the Vettes. Oil would seep into the guts of the pressure sensor and cause it to flake out and become erratic.
I’m not certain, but what I’ve inferred is that the ECM knows what pressure to expect at certain conditions and when it is sufficiently outside of the expected value, the p0521 code triggers.

I’ve replaced the sensor (had miswritten filter originally) and screen twice - once in June and the second in November - each time with OEM. It seems unlikely to me that each of the new ones would have gone bad that fast.
 
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