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

C

Cmobile

Joined
May 5, 2012
Messages
191
Location
Arizona
2013 Suburban 5.3L w/ 165k odo.

Vehicle is now my wife's daily driver and is short tripped. Once per week it gets on the highway (rural area) for ~37 miles round trip to the city. Rest is short trips in our little town 0.25-4 miles.

Changed oil with Havoline Pro DS 5w30 6qt box (Lifetime I think it says, or all mileage, marketing verbiage) about 1000 miles ago.

I got to drive last weekend and noticed hot idle oil pressure was around 23-26ish. Historically hot idle oil pressure is 37-38ish.

I changed the oil with the havoline DS Pro same as last time (bought the 3 pack) and oil pressure was back to normal.

Previous oil filter was Fram Endurance (been running them for several OCI's without issue. This time, due to convenience, I put in the O'Reilly Mictoguard premium. I really don't think it is filter related.

So, either fuel dilution from short tripps in cold weather, or perhaps the VOLM DoD spools/valves have some varnish?

A few oil changes ago I ran HPL EC. Did great at reducing oil consumption.

No sludge at last valve cover inspection, maybe 8 months ago.
Vehicle gets ~ 3k oil changes with full synthetic.

I have never had an issue running havoline Pro DS in the past, so I assume this is an engine issue. Prior to this Havoline I ran M1 ESP 5w30, and M1 HM 5w30.

Thanks

~C
 
The oil pressure will be lower when the oil viscosity is lower. It could be that your lower pressure reading was taken when the oil was a lot hotter, or that the oil was shear-thinned by the end of the OCI, or that there was fuel dilution. All of these factors combined could easily account for the 30-40% drop in oil pressure.

The other factor is the oil filter. If the oil pressure sensor is upstream of the oil filter, a filter with less restriction will result in a lower oil pressure reading. If the pressure sensor is downstream of the filter, the filter restriction wouldn't make a difference unless the oil pump was in pressure relief.
 
Oil probably sheared towards the 5w at the end of the interval. Likely nothing to worry about, particularly with 165k on the motor.
 
Here is the oil filter. Used side cutter and snips to "hack" it open

The pleats were even/parallel. I did spread them apart just to have a better look deep between the pleats.
Again, oil and filter had less than 1,000 miles on them

Oil pressure was observed from dash gauge. Engine temps were similar based on use and ambient temps. Low oil pressure observed while driving in the city, stop lights, (D) and in park with ambient temps about 40°F. Just normal errands, no hills, just mild city stop and go driving.

Retest after oil change with similar driving style and temps and time.

OEM Oil Sending Unit and screen eplaced maybe a year ago.

Probably just fuel dilution or oil degradation from short trips where engine never gets up to full operating temp.

I'm gonna start driving it 2x per week so I can get the oil up temp. The fuel savings of me driving the car are surely negated if I have to change the oil every 1k.

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.



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Cmobile said:
Here is the oil filter. Used side cutter and snips to "hack" it open

The pleats were even/parallel. I did spread them apart just to have a better look deep between the pleats.
Again, oil and filter had less than 1,000 miles on them

Oil pressure was observed from dash gauge. Engine temps were similar based on use and ambient temps. Low oil pressure observed while driving in the city, stop lights, (D) and in park with ambient temps about 40°F. Just normal errands, no hills, just mild city stop and go driving.

Retest after oil change with similar driving style and temps and time.

OEM Oil Sending Unit and screen eplaced maybe a year ago.

Probably just fuel dilution or oil degradation from short trips where engine never gets up to full operating temp.

I'm gonna start driving it 2x per week so I can get the oil up temp. The fuel savings of me driving the car are surely negated if I have to change the oil every 1k.

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.



View attachment 195103View attachment 195104View attachment 195105
Click to expand...
Wow that's ugly for such a short interval! Do you have any more HPL left?
 
I had the same thing happen on my wife's 2010 Yukon just before oil change at about the same mileage. I had put a Mobil 1 filter on it that one time because it was the only filter Wally World had on the shelf at the time (Covid era). In my wife's car the oil pressures were down about 10 psi across the rpm range and I was using the same PP 5w30 that I've run for the past 100K miles. Changing the oil and going back to an ACDELCO PF48 filter brought everything back to normal and the problem hasn't come back. I now keep a couple of PF48 filters in my stash so i always have one available.

My son's 08 Silverado has a 250K dirty, abused, oil swilling AFM 5.3 engine and one day his engine started losing all oil pressure after it ran a few minutes. Again we changed oil and filter and all was well again. As his mileage has accumulated his truck will often start losing oil pressure between oil changes. He changes the filter and drives on.

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.
 
OVERKILL said:
Wow that's ugly for such a short interval! Do you have any more HPL left?
Click to expand...
No more HPL, sadly. The filter has been out of the canister for over a week. Enough time to, "drip dry" (for lack of a better term) but I agree, looks like it was in there much longer.

So, moving forward. Car will be driven a bit more as I will take it to work a few days a week.
Now the question to myself is:
Continue to monitor the Havoline DS, testing oil filters if/when the pressure drops to determine if it is oil, or filter related, for curiosity sake?
Use a euro spec 0/5w30/40?
Use a HM M1 or equivalent ?
Ponder the benefits of HPL, evaluate ROI?
Buy a new Lexus and not worry, but be car broke? Jk not happening.
 
Your mileage is also about the time the oring on the oil pickup tube starts to fail. Typical symptoms you are having. Or, looking at your oil filter the engine does not look to be very clean inside so maybe the oil press sensor screen is clogged or sensor starting to go bad again.
 
Gyro Gearloose said:
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.
Click to expand...
🤣 so true.
There is a release/relief in the drain pan that relieves the flow from the VOLM. Not exactly sure when it opens or at what pressure, but this vehicle has the shield installed (TSB for consumption)

That's why I thought, and still wonder, if there is varnish/gum (coking) somewhere in the DOD cylinder deactivation system.
I know how to resolve it, HPL has been proven, but, I am trying to justify the cost for the short OCI's.

Decisions, Decisions
 
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.
 
GMBoy said:
Your mileage is also about the time the oring on the oil pickup tube starts to fail. Typical symptoms you are having. Or, looking at your oil filter the engine does not look to be very clean inside so maybe the oil press sensor screen is clogged or sensor starting to go bad again.
Click to expand...

I have read, no facts, just Internet lore, but symptoms of that O-ring going bad was lower cold start up pressures when oil cold, but improved as the oil reached operating temps. Not sure tho.

It was in early 2022 that HPL EC went in. Here the post with a pic of valve covers at the time. I was driving it back then, and it had started consuming oil excessively. I think the mileage was maybe 148K miles At the time.

High Performance Lubricants Engine Cleaner

Since the topic has come up a few times I am posting the PDS in the PCMO, Diesel, and Euro sections. This is a safe path to clean varnish and or sludge left behind by other oils. There are no solvents in this oil. It has enough ester to clean but still be safe with elastomers. Simply add a quart...
bobistheoilguy.com

Valve covers were thoroughly cleaned prior to being reinstalled.

Grandkids and family coming in later this week, for the holidays, so I will try to pull the covers to see what condition my condition is in🎵 after the New Year
 
After reviewing the previous thread from 2022, the valve cover did not solve the oil consumption. I just neglected to update. It helped a little. HPL EC reduced it I think by more than half. After HPL was short OCI's and (an Over the Counter stiction eliminator additive). After all that, 3-3.5k OCI's had negligible consumption. Just a hair below the full mark.
 
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