Question about RPM's & oil pressure

[rav3]

Good afternoon, guys....

I have a question for you knowledgeable wrencher about my 2017 Silverado, 5.3L V8, 6 speed transmission fully equipped with MAX Towing Package.

 

I noticed with this package, and maybe with all other models, that when going downhill, when computer senses this, I will get the message on the dash that the "GRADE BRAKING" is engaged and the transmission down shifts, 1 or 2 gears. I understand this & know how to disengage if I want to.

What my question is...once the RPMs reaches about 3500, the oil pressure automatically jumps to about 60 PSI. If i brake & slow the truck down, once the RPMs reduce to below 3500, it goes back to normal (40-45 ish PSI).

Does anyone know why the engineers designed this input feature into these trucks? Does it have anything to do with DOD/AFM? or is it just to get more oil to wear items?

As a retired engineer, I know there's a good reason why some team put this feature into the ECU, just curious what the thinking or logic was behind it or if it's because of the DOD/AFM?

BTW, I run the RANGE DOD delete, which turns this feature off, just in case it means anything.

 

Thanks for any info....

[Yotaman]

Subscribed...

[CamGTP]

The oil pump is a two stage variable pump, the second "stage" kicks in around that 3,500rpm. More oil flow at higher rpm makes it better for engine bearings and metal to metal parts. Keep cooling at it's maximum with more oil flow.

[newdude]

Cam nailed it.  All the Gen 5 V8s have these variable dual stage pumps as do many other GM engines that have arrived on scene the last 5-8 years.  

Edited December 8, 2022 by newdude

[Grumpy Bear]

Hot oil pressure minimums.
22 psi @ 1,000 rpm
30 psi @ 2,000 rpm
33 psi @ 3,000 rpm
LV1, LV3, L83, L86 and L96.  
 

[customboss]

16 hours ago, Grumpy Bear said:

Hot oil pressure minimums.
22 psi @ 1,000 rpm
30 psi @ 2,000 rpm
33 psi @ 3,000 rpm
LV1, LV3, L83, L86 and L96.  
 

Add the L3B when you can...... :>)  

[customboss]

On 12/3/2022 at 3:38 PM, CamGTP said:

More oil flow

Yep, NOT PRESSURE which = restriction to FLOW.  

[Grumpy Bear]

54 minutes ago, customboss said:

Add the L3B when you can...... :>)  

 

Don't have that RPO. Got the ones I have from @newdude a long time ago. Sorry  

[customboss]

10 minutes ago, Grumpy Bear said:

 

Don't have that RPO. Got the ones I have from @newdude a long time ago. Sorry  

I can't find the data but at hot idle it can be < 20 psi easy. Scanner won't read it, analog gauge is hard for me to trust. 

[16LT4]

Question for the fluid engineers out there: when grade braking, using the engine's compression and internal friction to resist gravity free-wheeling an increased engine speed, wouldn't running the oil pump and higher pressure help hypothetically keep the load from increasing the engine's RPM increase?  Or, said another way, improve grade breaking by helping keep RPM down due to increased internal drag?  Or would the beneficial effect be marginal, if at all?

Edited December 10, 2022 by 16LT4