Oil Pressure: What is it?

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rg200amp

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Hello all. Found this guys Youtube channel, and he as A LOT of great vids.

There's been some talk about oil pressure around the board. And I saw this vid about a week ago. Some very interesting info!



More of his stuff can be seen at Ericthecarguy.com
 
Say an engine with 300,000 miles has trouble maintaining oil pressure. The engine is spec'd to run a 5w30 oil. Would increasing the thickness of the oil i.e. 15w40 or 20w50 help to increase oil pressure?
 
Originally Posted By: outoforder
Say an engine with 300,000 miles has trouble maintaining oil pressure. The engine is spec'd to run a 5w30 oil. Would increasing the thickness of the oil i.e. 15w40 or 20w50 help to increase oil pressure?


It may indeed as it is thicker, thus it may take more effort to get squeezed through the worn clearances if you indeed do have worn clearances. . . . . . .

But, will it be effective for cooling, cylinder lube, cam lube, VVT operation (if equipped), ect. . . . .

Lots of things to consider. . . . But it may be something to consider if your in that situation. . . .
 
I have a 99 Rodeo that consumes a quart of oil every 500 miles using 10W-30. I switched to 15W-40 and it consumes oil at about a quart every 2,000 miles and I have noticed the oil pressue has gone up some what.
 
I didn't watch the video but it's the clearances of the engine that create the oil pressure not the oil pump. So yes using a little thicker oil in a worn engine will increase oil pressure a little.
 
Originally Posted By: outoforder
Say an engine with 300,000 miles has trouble maintaining oil pressure. The engine is spec'd to run a 5w30 oil. Would increasing the thickness of the oil i.e. 15w40 or 20w50 help to increase oil pressure?


Yes, but the engine would still be worn!

Back in the day, when STP was king, thickening the oil of a high mileage engine did indeed raise the OP to acceptable levels, and it might even quieten a noisy engine. But it ONLY masked the SYMPTOMS of wear.
Now, having said that, in the short term, that may well be better than letting the old engine 'beat itself to death' hammering on a thin oil.
But it was not a rebuild in a can.
 
Originally Posted By: motor_oil_madman
I didn't watch the video but it's the clearances of the engine that create the oil pressure not the oil pump. So yes using a little thicker oil in a worn engine will increase oil pressure a little.


The oil pump creates the pressure. The actual pressure is determined by the rate at which it's pumped, the clearances in the engine, and the viscosity of the oil.
 
Originally Posted By: hate2work
Originally Posted By: motor_oil_madman
I didn't watch the video but it's the clearances of the engine that create the oil pressure not the oil pump. So yes using a little thicker oil in a worn engine will increase oil pressure a little.


The oil pump creates the pressure. The actual pressure is determined by the rate at which it's pumped, the clearances in the engine, and the viscosity of the oil.


According to Eric it does not.

The oil pump pumps the oil like a pressure washer pumps water. What creates the pressure is the small tip at the end of the nozzle. For if the line and nozzle openings on the pressure washer were as large as a coffee can, that same pump would just allow water to flow out with little to no pressure. . . . .

But I see what your saying. The harder/faster the pump "pumps" can produce more pressure. But I think we are talking about a standard oil pump for a car. If you have low oil pressure, a pump replacement will not cure it if the tolerances in the engine are what is causing the drop. Because the new pump will pump the same amount of oil as the old pump.
 
Last edited:
Originally Posted By: hate2work
Originally Posted By: motor_oil_madman
I didn't watch the video but it's the clearances of the engine that create the oil pressure not the oil pump. So yes using a little thicker oil in a worn engine will increase oil pressure a little.


The oil pump creates the pressure. The actual pressure is determined by the rate at which it's pumped, the clearances in the engine, and the viscosity of the oil.


The term "create" is poorly chosen. You can save yourself a lot of words by saying pressure is resistance to flow.
 
If the lack of oil pressure is due to the oil flowing out of the worn bearings, yes, match the oil viscosity to the bearing clearances. If the lack of oil pressure is due to a worn oil pump, clogged pick up screen, or other problem in the oil supply, no higher viscosity oil won't help.
 
Originally Posted By: Bad_Robot
Originally Posted By: hate2work
Originally Posted By: motor_oil_madman
I didn't watch the video but it's the clearances of the engine that create the oil pressure not the oil pump. So yes using a little thicker oil in a worn engine will increase oil pressure a little.


The oil pump creates the pressure. The actual pressure is determined by the rate at which it's pumped, the clearances in the engine, and the viscosity of the oil.


The term "create" is poorly chosen. You can save yourself a lot of words by saying pressure is resistance to flow.
I like this. Clear and accurate. The definition in the video somewhat misses the mark.
 
Pressure is the restriction of flow. Very basic,,,The oil pump moves the oil. The clearances between the parts causes the pressure
 
Originally Posted By: Steve S
Pressure is the restriction of flow. Very basic,,,The oil pump moves the oil. The clearances between the parts causes the pressure



OH MY GOD!!THANK YOU!!!

it really is that simple folks. the greater the clearance, the thicker the oil you need to keep pressure. when your high mileage engine starts loosing pressure little by little or fluctuating, step up to the next grade. its not to mask a problem, its too keep the engine going so you can get the maximum amount of miles between rebuilds.

remember the old saying keep it simple stupid.
 
Originally Posted By: outoforder
Say an engine with 300,000 miles has trouble maintaining oil pressure. The engine is spec'd to run a 5w30 oil. Would increasing the thickness of the oil i.e. 15w40 or 20w50 help to increase oil pressure?


the right answer here is yes. and when you hit 400k if it looses pressure or fluctuates with 20/50 try a high volume oil pump with the 20/50
 
Without an oil pump, engine bearings have no pressure.
With tight/narrow bearing clearances, there still is no pressure with no oil pump.

We can certainly increase gauge pressure readings with tighter clearances OR a more powerful pump.
 
Originally Posted By: mechtech2
Without an oil pump, engine bearings have no pressure.
With tight/narrow bearing clearances, there still is no pressure with no oil pump.

We can certainly increase gauge pressure readings with tighter clearances OR a more powerful pump.


your wrong here. the only thing that regulates pressure is the oil pump relief spring. its set to relieve pressure at a certain pressure. the only way to increase the stock pressure would be to buy a high pressure pump or change the spring

so if your crank was sealed to your rods and mains you would still only have stock pressure because the pump would by pass. when stock pressure can no longer be achieved its because the gaps are loosing too much oil for the volume of the pump to overcome, where as the remedy would be a thicker oil or higher volume pump.

every car has an oil pump that can give more pressure than it needs(hence the by pass). the pumps go into by pass all the time and as the engine ages and clearances increase it goes into by pass less and less because it is having to pump more volume.

hope that shed some light for ya
 
"the pumps go into by pass all the time"

I disagree, normally the pump will only go into bypass in the first few minutes after staring or if higher revs are used before the oil is fully warm.
Bypass pressure is normally somewhere in the region of 80psi even a new engine (When warm, at moderate RPM) would register pressure something like half that.

I guess I should add 'Typically' in there.
 
Last edited:
Originally Posted By: electrolover
Originally Posted By: mechtech2
Without an oil pump, engine bearings have no pressure.
With tight/narrow bearing clearances, there still is no pressure with no oil pump.

We can certainly increase gauge pressure readings with tighter clearances OR a more powerful pump.


your wrong here. the only thing that regulates pressure is the oil pump relief spring. its set to relieve pressure at a certain pressure. the only way to increase the stock pressure would be to buy a high pressure pump or change the spring


Mostly correct but you didn't mention a high volume pump that usually have a stock pressure relief but use larger gears to increase flow... Those can increase hot pressure while still maintaining a max cold pressure of the stock pump... A high pressure pump(that may well have larger gears and heavier spring), will generally increase pressure at all temps...
 
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