Oil pressure low

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.

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

Angelo217 said:

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

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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.

rockola1971 said:

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

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rockola1971 said:

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

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Houston

15burban said:

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.

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5-30 high mileage.

What brand?

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.

strutaeng said:

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

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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.

15burban said:

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.

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

Angelo217 said:

Using synthetic high mileage 5W30

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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.