Oil change resolved hot idle lower oil pressure., why?

[xmanjeff]

with the gm 5.3 in around the years of yours ,there was a filter change i believe , something to do with a change in bypass pressure ,
if you research ,there are oodles of posts on this same question and topic, but looks like you are on top of it

 

[Cmobile]

The only larger filter I am awaee of, is for the 2015 and up GM 5.3l. It's a little longer maybe 3/4".
However it has a 22psi bypass rating instead of the 16psi for th 13 model year.

Frams website now shows that the 22psi range is suitable for the 2013 suburban

 

[Cmobile]

with the gm 5.3 in around the years of yours ,there was a filter change i believe , something to do with a change in bypass pressure ,
if you research ,there are oodles of posts on this same question and topic, but looks like you are on top of it

Yea, initially yhe change was for the 2-stage oil pumps. Mine does not have that. It increased the bypass from 16 to 22 psi.

According to Frams website, 22 psi is now acceptable tor this engine.

 

[Faawrenchbndr]

For reference, the relatively new AGM battery had a low SoC. State of charge. I put the battery on the charger/conditioner every 2 months or so as a PM. When I did it last it took about 5 hours to get it fully charged. Usually gets full within 2 hours. That's an indication of too many short tripps.

unless you have gotten your charging system tweaked, the AGM battery will never fully charge. It has nothing to do with short trips, voltage supplied just isn’t high enough

 

[4WD]

Yea, initially yhe change was for the 2-stage oil pumps. Mine does not have that. It increased the bypass from 16 to 22 psi.

According to Frams website, 22 psi is now acceptable tor this engine.

Yep - gave the BiL my older XG10575’s for his Ford - then once they changed the XG10575 (my cut open was not appealing) - have moved on to other filters …

 

[Cmobile]

unless you have gotten your charging system tweaked, the AGM battery will never fully charge. It has nothing to do with short trips, voltage supplied just isn’t high enough

Just wanted to clarify. I have a bench charger that I put my batteries on every few months. Normally takes maybe 2 hours to bring them to full soc.
Recently, it took several hours in this case.

When a car is started, it pulls a lot of amps. If the car doesn't run long enough to replenish the charge, there is a deficit. Little by little, the battery gets lower SoC.

 

[OVERKILL]

Known issue with these engines and the recent HEMI, when running higher efficiency filters. These engines load the filters with debris, resulting in a drop in oil pressure.

Amsoil has a bulletin about this issue.

Yeah, that's what I'm thinking looking at how ugly that filter is, but it shouldn't have gotten plugged up in 1,000 miles.

And of course we've got a bit of a catch-22 here as if you are cleaning, you want to be catching that material, not letting it circulate.

The use of the EC to effectively reduce oil consumption leads me to think there are some considerable deposits in this engine. If he runs their oil, it should improve (reduce) the consumption further, but what that will liberate, in a relatively short period of time, is a huge wildcard, being far more aggressive than the EC. We've seen what has come out of what were "clean" engines (my wife's truck, @wwillson's Durango...etc) so this would be far, far worse.

 

[twX]

It's like the 5.3 has a secret bypass valve somewhere upstream of the filter that is set lower than the filter bypass and it bleeds off the oil pressure when the filters start to clog. I know that sounds illogical but I can't think of another explanation.

A clogged filter will cause a drop in oil pressure downstream of the filter if the oil pump is bypassing, since flow will be reduced when there is more restriction. Some vehicles are designed with oil pumps that will start bypassing when the engine speed is not much higher than idle, even when the oil is warm. This seems to be the case with a lot of American engines that run high oil pressures at idle.

Here's an example from an Australian Ford Falcon 4.0L turbo inline-6. The oil pump is bypassing at under 1,000 rpm when the oil at 80°C. If the filter were clogged, it would happen at an even lower rpm. On engines like this, restrictive filters will cause low oil pressure and low flow.

If filter clogging is an issue, I'd use a filter with low restriction and high holding capacity, like a Purolator BOSS, Wix XP, or NAPA Platinum. An oversized filter may be better. Also, don't use a filter that has a higher bypass pressure rating than OEM, or one that has a tiny bypass valve.

 

[StumblingElk]

I experienced this exact phenomenon in my 5.3 except short trips were not at play.

Fuel dilution was not present in my motor

Long story short based on my experience the engine /oil was dirty and clean oil with some AT205 (and subsequent frequent oil changes) helped dramatically to bring oil pressure back up.

Filter brand has been supertech and Fram XG and oil has been supertech. Filter brand made no difference and neither did playing with the weight of the oil. Heads looked very clean given the mileage when covers were removed; no sludge

 

[Cmobile]

Today, I took the Burb to run errands. Drove to nearby town ~17 hwy miles, dash temp showed 37°. When I got got in the city, first stop light, oil pressure was around 26ish again. Current oil is still amber and has maybe 150 miles on it.

(Edit) so the historical "normal" oil pressure I was used to seeing was short lived. Had at least 40 min of driving after oil change with alleged normal oil pressure. Now it is relatively low (27ish) with about 150 miles on oil.

Soooo, there goes all my preconceived notions.

I bought 2 oil filters this morning. AC Delco PF48 and Fram Endurance FE10575, for 2015 MY(which is slightly longer than the FE10060 spec'd for my MY.)

Fram states FE10575 18-24psi for bypass. 2015 MY
And FE10060 22psi for bypass. 2013 MY.

So I'm comfortable running the larger filter.

should I install one of these newly purchased filters without oil change to see if it makes a difference? In the interest of gathering data and troubleshooting.
If so which should I try first, if any?

Next steps??
- HPL EC?
- 6 quarts of HPL oil?
- change to euro M10w40 FS?

My plan.
I am ordering a new AC Delco sending unit and screen. Just to rule it out as an issue. Will also pull valve covers to have a look and take pics before changing oil, after the New Year.

 

[StumblingElk]

Today, I took the Burb to run errands. Drove to nearby town ~17 hwy miles, dash temp showed 37°. When I got got in the city, first stop light, oil pressure was around 26ish again. Current oil is still amber and has maybe 150 miles on it.

(Edit) so the historical "normal" oil pressure I was used to seeing was short lived. Had at least 40 min of driving after oil change with alleged normal oil pressure. Now it is relatively low (27ish) with about 150 miles on oil.

Soooo, there goes all my preconceived notions.

I bought 2 oil filters this morning. AC Delco PF48 and Fram Endurance FE10575, for 2015 MY(which is slightly longer than the FE10060 spec'd for my MY.)

Fram states FE10575 18-24psi for bypass. 2015 MY
And FE10060 22psi for bypass. 2013 MY.

So I'm comfortable running the larger filter.

should I install one of these newly purchased filters without oil change to see if it makes a difference? In the interest of gathering data and troubleshooting.
If so which should I try first, if any?

Next steps??
- HPL EC?
- 6 quarts of HPL oil?
- change to euro M10w40 FS?

My plan.
I am ordering a new AC Delco sending unit and screen. Just to rule it out as an issue. Will also pull valve covers to have a look and take pics before changing oil, after the New Year.

Have you ruled out the pickup O-Ring being bad?

 

[Cmobile]

Have you ruled out the pickup O-Ring being bad?

I have not rulled it out. Just hoping to find a les expensive repair if one is available.

There are posts on a few forums that mention, if oil pressure is low at start up when cold, but returns to somewhat normal at operating temp, it is likely the pickup tube O-ring.
Not sure if this is entirely valid tho. I seem to have the reverse issue, where hot oil pressure is low.

But may have to go this route & weigh the cost of repair. There are posts that mention, their hot oil press has been 25ish for as long as they can remember, engine still going good for them.
I am just concerned that it was 10-12 psi higher, now it's not.

So if I do have the pickup tube replaced, seems to me that would also be the time to replace the oil pump, harmonic balancer, and associated seals. Sounds expensive as I wont be performing this kind of repai myself .

 

[mrbreezeet1]

TLDR!!
It's not really, but I didn't read it.
I'm just going to add my 2 cents and confusion too probably!
Because it lost its viscosity! (OMG I spelled that right!)
Simply put it was too thin. The new oil is thicker with more body, and tightened up the bearing clearance a bit.

 

[twX]

(Edit) so the historical "normal" oil pressure I was used to seeing was short lived. Had at least 40 min of driving after oil change with alleged normal oil pressure. Now it is relatively low (27ish) with about 150 miles on oil.

You may be chasing a problem that doesn't exist. What does GM spec for oil pressure at warm idle on your engine? A quick google search tells me 22 psi at 1,000 rpm. Not completely sure if this is the correct spec for your engine, but if it is, your oil pressure is fine. In fact, it's a bit high if your idle speed is lower than 1,000 rpm, and it was much too high at 37-38 psi before.

Higher oil pressure isn't always better. It can be an indication of excessive restriction in the oiling system. If the engine's been getting cleaned up from the HPL and short OCIs, that might be what caused the oil pressure to drop, and it's a good thing.

Oil viscosity will drop 20% with every 10°C rise in temperature, and idle oil pressure will drop by around the same amount. The gauge on your dash may not be all that accurate either. Not sure how good your memory is, but it might not be that good either. If you really want to know if your oil pressure is normal, use a proper oil pressure gauge, use the test procedure in the service manual that details the proper rpm and engine warm up procedure to use, then compare your readings to the spec.

 

[StumblingElk]

I have not rulled it out. Just hoping to find a les expensive repair if one is available.

There are posts on a few forums that mention, if oil pressure is low at start up when cold, but returns to somewhat normal at operating temp, it is likely the pickup tube O-ring.
Not sure if this is entirely valid tho. I seem to have the reverse issue, where hot oil pressure is low.

But may have to go this route & weigh the cost of repair. There are posts that mention, their hot oil press has been 25ish for as long as they can remember, engine still going good for them.
I am just concerned that it was 10-12 psi higher, now it's not.

So if I do have the pickup tube replaced, seems to me that would also be the time to replace the oil pump, harmonic balancer, and associated seals. Sounds expensive as I wont be performing this kind of repai myself .

Have the truck idle at an incline (nose down) and also flat and see if oil pressure changes.

The idea being that the oil in the pan needs to be above the pickup o-ring, negating the o-ring altogether. You may need to add a qt or so of oil into the crankcase depending on your exact setup to accomplish this. Just be sure to check oil pressure when truck is level, as well.

If pressure goes up when truck is inclined then the o-ring is very likely bad. You might get lucky if the ring isn't torn (just dried up) and be able to limp it along for a while by adding AT205 at every oil change. But it is very likely it would need immediate replacement.

 

[The Critic]

Yeah, that's what I'm thinking looking at how ugly that filter is, but it shouldn't have gotten plugged up in 1,000 miles.

And of course we've got a bit of a catch-22 here as if you are cleaning, you want to be catching that material, not letting it circulate.

The use of the EC to effectively reduce oil consumption leads me to think there are some considerable deposits in this engine. If he runs their oil, it should improve (reduce) the consumption further, but what that will liberate, in a relatively short period of time, is a huge wildcard, being far more aggressive than the EC. We've seen what has come out of what were "clean" engines (my wife's truck, @wwillson's Durango...etc) so this would be far, far worse.

Yeah, without an autopsy, it is hard to say. But we have to keep in mind that not all filters flow the same way, and different medias can respond differently to debris loading.

FWIW, I gained about 5 psi on my truck after replacing a 5k old ACDelco Ultraguard with a new Mopar rock stopper.

 

[Cmobile]

Following advice, despite being hard headed., I pilled the OSU and screen. Screen is clean and clear. OSU, on the other hand had oil on the terminal side.
Headed to Autoparts store chain to try and get a replacement. Hoping for OEM, but will have to take what I get.

will report back after its replaced

 

[Faawrenchbndr]

Just wanted to clarify. I have a bench charger that I put my batteries on every few months. Normally takes maybe 2 hours to bring them to full soc.
Recently, it took several hours in this case.

When a car is started, it pulls a lot of amps. If the car doesn't run long enough to replenish the charge, there is a deficit. Little by little, the battery gets lower SoC.

Just stating, your justification for the battery charge was the short trips. That’s not the case of you haven’t modified the stock charging system voltage.


But yes, a bench charge will save the battery

 

[Cmobile]

Just stating, your justification for the battery charge was the short trips. That’s not the case of you haven’t modified the stock charging system voltage.


But yes, a bench charge will save the battery

I see your point. I didn't state it clearly.

No changes to alternator charging system.

I put the external charger on all my vehicles every few months. The point I intended to make was:
Usually full SoC in couple hours when on the bench charger. This past charge on the suburban, took significantly more time until my charger said "Full".

So I inferred that short trips left the battery with more of a deficit SoC.

 

[Cmobile]

New AC Delco OSU installed, clean oil screen.

Hot idle shows 26-27 ish.

Took a hot minute to clean the oil out of the connector. May need to replace the connector.

On another note. Here is a pic from down the oil fill neck. Couldn't quite get the inspection camera to go where I wanted it to.