Oil pressure low

[Angelo217]

2006 Chevy Tahoe 5.3L 233k miles

Using synthetic high mileage 5W-30
Had truck for 13k miles
Noticed lower pressure upon purchase in may 24 (Now November 24)

Truck gets okay oil pressure after a fresh oil change just did one so just below 40 at idle currently after an oil change 10 miles ago.

Pressure drops as it warms up, will continue to get lower and lower as the oil degrades. Begins to droop below 20 after I’d say roughly 3k miles on the oil.

I’ve already done the pickup tube o ring. Pickup tube is clean and not clogged.

Oil pressure sensor assumed to be working (hooked up autel scan tool to OBD, shows sensor is reading accurate.)

No excessive engine noise, or strange noise, no knocking no ticking. Smooth motor. Feels underpowered compared to other 5.3’s I think it’s unrelated.

Does this point fingers to the oil pump or bearing wear? Or what else should I check thanks

On average in between changes I’m hovering at 28-32 or so maybe on the highway. At 80 MPH.
High 30’s cold idle.
20 and below warm idle.

Will shoot slightly above 40 upon heavy acceleration In between changes, if the oils getting older it won’t even go above 40.

 

[rockola1971]

Really the only one that sticks out to me is the 20 and below at warm idle. Where are you located?

 

[15burban]

Oil pressure sensor assumed to be working (hooked up autel scan tool to OBD, shows sensor is reading accurate.)

Your scan tool is only going to tell you what your sensor is reading. It doesn't have its own source to get that data from. It is a good way to see if your gauges are recording accurately from what your sensor is reading though.

Sorry I can't be of more help besides possibly try a heavier 30 weight oil or a 40wt.

What kind of oil are you using? Just curious. Possibly it's a light 30wt and shears down to a 20wt.

 

[Angelo217]

Really the only one that sticks out to me is the 20 and below at warm idle. Where are you located in

Really the only one that sticks out to me is the 20 and below at warm idle. Where are you located?

Houston

 

[Angelo217]

Your scan tool is only going to tell you what your sensor is reading. It doesn't have its own source to get that data from. It is a good way to see if your gauges are recording accurately from what your sensor is reading though.

Sorry I can't be of more help besides possibly try a heavier 30 weight oil or a 40wt.

What kind of oil are you using? Just curious. Possibly it's a light 30wt and shears down to a 20wt.

5-30 high mileage.

 

[15burban]

What brand?

 

[strutaeng]

80 MPH 28-32 psi does seem kinda low. What RPM is this?

I'm not understanding why you mention the oil pressure drops between oil changes. That kinda puzzling TBH.

But 233k is getting up there on the mileage. I would switch to the next weight of oil and keep running it. Your bearings most likely have some wear.

 

[15burban]

I'm not understanding why you mention the oil pressure drops between oil changes. That kinda puzzling TBH.

Thats why I question the oil. All the vehicles I've had the pressure has stayed the same from the first start up on a fresh oil change to the last one before it was changed again.

 

[strutaeng]

Thats why I question the oil. All the vehicles I've had the pressure has stayed the same from the first start up on a fresh oil change to the last one before it was changed again.

It's pretty simple to rule out the oil. Just switch brands for the next oil change.

 

[Marky Dissod]

Using synthetic high mileage 5W30

Believe it or not, this is quite imprecise.
Since winter is coming, I recommend NON-high mileage 5W30 synthetic from Mobil1, Valvoline, Quaker State, or Pennzoil.
(I won't use Castrol even if I get it for free
If the only symptom is oil pressure which is on the low side of acceptable, you need to measure oil pressure at some other point,
maybe that spot has a partial blockage which is showing locally low oil pressure?

If your radiator has a motor oil heat exchanger, oil pressure will go up slightly once you bypass it.
So long as you keep using synthetic this should not be an issue even if your engine works or plays hard.

 

[15burban]

It's pretty simple to rule out the oil. Just switch brands for the next oil change.

Even oil filters can help raise oil pressure. Given the op has only said 5w30 high mileage makes me think a quick change oil place. Which at least around me use the cheapest of oil and oil filters. I'd never heard of the brand "mighty" for oil filters until I had to change out a lower radiator hose in my mom's expedition who goes to one of the quick change places. Not only did the inside of the filter look very cheap it was also close to half of the size of the filter that my local oreillys called for for her motor.

 

[Angelo217]

Believe it or not, this is quite imprecise.
Since winter is coming, I recommend NON-high mileage 5W30 synthetic from Mobil1, Valvoline, Quaker State, or Pennzoil.
(I won't use Castrol even if I get it for free
If the only symptom is oil pressure which is on the low side of acceptable, you need to measure oil pressure at some other point,
maybe that spot has a partial blockage which is showing locally low oil pressure?

If your radiator has a motor oil heat exchanger, oil pressure will go up slightly once you bypass it.
So long as you keep using synthetic this should not be an issue even if your engine works or plays hard.

I’m going to replace the pressure sensor and either remove or replace that screen entirely. Will see what that does. If that does not resolve my issue I forgot to mention I do have a pretty bad rear main leak. But according to my research it shouldn’t bleed as much pressure as I’m losing now. But once I replace those two items i believe im left with the oil pump itself, or unfortunately bearing wear which to me seems highly unlikely as this truck was owned by two very old ladies. And did their oil changes on time judging by the very clean state of the oil pan with virtually no sludge. Original gasket on it the pan has never been dropped before I did it.

 

[Angelo217]

Even oil filters can help raise oil pressure. Given the op has only said 5w30 high mileage makes me think a quick change oil place. Which at least around me use the cheapest of oil and oil filters. I'd never heard of the brand "mighty" for oil filters until I had to change out a lower radiator hose in my mom's expedition who goes to one of the quick change places. Not only did the inside of the filter look very cheap it was also close to half of the size of the filter that my local oreillys called for for her motor.

I work at an oil change place. It is a full service shop as well. I used a wix XP filter, and we used pennzoil motor oil. The high mileage comes in a box. Not faked with some cheap alt conventional. So it’s good quality oil. I always do my changes myself.

 

[Angelo217]

Even oil filters can help raise oil pressure. Given the op has only said 5w30 high mileage makes me think a quick change oil place. Which at least around me use the cheapest of oil and oil filters. I'd never heard of the brand "mighty" for oil filters until I had to change out a lower radiator hose in my mom's expedition who goes to one of the quick change places. Not only did the inside of the filter look very cheap it was also close to half of the size of the filter that my local oreillys called for for her motor.

And so after a few days on this oil change right now completely warmed up 15 minutes of driving I idle at about 28-30 it looks like. Completely fresh clean oil.

 

[rockola1971]

And so after a few days on this oil change right now completely warmed up 15 minutes of driving I idle at about 28-30 it looks like. Completely fresh clean oil.

Those value look perfectly normal for the mileage you have. What does the pressure goto when cruising at 55pmh? How about idle to 35 mph? Do you have a standard 3.73 rearend?

 

[Mudsport96]

I have noticed a pressure issue with certain filters. I always run a ac Delco now. But during the vid there was a couple times I couldn't get them so I ran the orielly filters and had the exact same symptoms he is describing. Try switching the wix for a Delco. I know wix are good, but it is something easy to rule out

 

[Marky Dissod]

Wix 51522MP, not merely 51522.

 

[SilverSport]

...and Mann+Hummel owned Wix may not be what they once were...

Bill

 

[Marky Dissod]

... and Mann+Hummel owned Wix may not be what they once were ...

That's one reason why I never settle for the 'basic' filter offered by any brand. I.E.:
instead of Fram's PH3675, try XG3675 or TG3675
instead of Purolator's L25288, try PBL25288
instead of Wix's 51522, try 51522MP.

Willing to risk wasting a few extra bucks per oil filter for a better oil filter.
If I find out Wix has been slipping like Castrol's been slipping for the past 2 decades,
then I'll stop buying Wix entirely.

 

[houstontaylor]

Mine was recently intermittently going down to 20 psi before I replaced the oil pressure sensor. Maybe the heat when the engine is warmed up is affecting the sensor but I don't know about the new oil/old oil aspect.