2013 BRZ - Two UOAs (GC0w30 and Toyota SN 0w20)

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Like I said, circular "logic".

You can't equate an engine to the flow of a viscous fluid through a straight pipe, when the "pipe" friction is not what what the pressure drop actually reflects.

Given that you are pretty au fete with hydrodynamics, pick an oil line of (say) 15mm, and a metre length, and a flow rate of 4GPM, and calculate the pressure drop along the pipe...it's nothing compared to the pump discharge pressure...easy to prove, off you go...

Even the least scientific BITOGer acknowledges that the oil pressure is the resistance (backpressure)to moving oil through the bearings, not the flow restriction through the galleries.

As to bearing lubrication being non-hydrodynamic, the GF-6 specs, which are nearly totally aimed at very low viscosity (in particular HTHS) are showing that engines are moving INTO boundary lubrication in the search for economy, which is an increasingly common phenomenon, not common in previous designs and lubricants.

http://www.stle.org/resources/articledetails.aspx?did=1671

http://oil-additives.evonik.com/sites/dc...t-davidgray.pdf
 
Originally Posted By: Shannow
pick an oil line of (say) 15mm, and a metre length, and a flow rate of 4GPM, and calculate the pressure drop along the pipe...it's nothing compared to the pump discharge pressure...easy to prove,
As Charlie Brown would say, Aaugh!
The pressure drop is a given!
Anyway, I am happy you note that things are moving into boundary lubrication and out of hydrodynamic with modern lubricants.
I dare to say, and I could be wrong, that these new style lubricants will work wonders even on older engines, maybe with an upgrade to the oil pump for more volume.
 
OK, you've defined the pressure drop as a given...calculate the flow through said 15mm pipe, 1M long, and tell me how THAT compares to the typical flow rate of a typical engine positive displacement oil pump...

I have always acknowledged that engines, with their lower operational viscosity, are seeing more boundary lubrication...it's not what you would target if you were buying said vehicle.

Originally Posted By: nickolas84
I dare to say, and I could be wrong


You scored that one in spades...

Flow <> lubrication...ever...unless you've got better science.
 
Originally Posted By: JAG
Originally Posted By: nickolas84
BITOG recently published "Motor Oil University". You can check it here MOTOR OIL UNIVERSITY. It goes through all of this and the benefits of modern "synthetic" thin oils in great detail.

This is one more case of someone thinking that what they read on the internet is true. Those articles seem to fill some people with more falsehoods than they had before they read it. At the same time, their estimate of their knowledge on the subject increases, and then they become not only more "wrong", but more confident that they are not wrong. One forum member wrote those articles. BITOG should not have posted them, in my opinion.


Originally Posted By: OVERKILL
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BITOG recently published "Motor Oil University". You can check it here MOTOR OIL UNIVERSITY. It goes through all of this and the benefits of modern "synthetic" thin oils in great detail.


As others have stated, that's not recent. It is a relatively old series of articles written by a resident poster, who is a plastic surgeon by trade. A very intelligent man but as JAG has noted, these dissertations that he's authored have resulted in many people thinking they know a lot more than they actually do. And getting many of the fundamental concepts completely wrong.


I am wondering ... are you considering what AEHaas has written, about 6 years ago, wrong or just prone to misunderstanding and misinterpretation ?

As I remember he has written that more pressure does not give better lubrication but more flow does.
 
Originally Posted By: nickolas84
@Garak that is the reason I am referring to rpm the relief valve opens with warmed up oil and not pressure numbers.

That is a bit of a problem. Without knowing these things in practice, it's just a bunch of guessing and hypothetical talk.

As for the Hagen–Poiseuille equation, do the calculation Shannow requested.
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Nonetheless, you're oversimplifying and overextending the application of the equation.

Originally Posted By: mesastoura
As I remember he has written that more pressure does not give better lubrication but more flow does.

As already mentioned, "flow" is only one aspect to lubrication. You don't automatically get better lubrication by more "flow." Of course, we've already discussed how you can't just magically increase flow by decreasing viscosity. There are plenty of advantages to low viscosity lubricants. We don't have to invent advantages.

Motor Oil University articles are NOT a valid source for trying to upend the apple cart.
 
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I asked the OP to post his UOA here and I'm sure he would be happier if there was this much discussion and debate about his particular uoa.
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-Dennis
 
Originally Posted By: nickolas84
The BMW story as I know it is different (click) and stemmed from bearing failures with the 10W-60 oil because of tight bearing clearencess.


That's one THEORY and pertains to a particular series of M3. BMW has been using TWS (10w-60) for a very long time, and before that used an almost as heavy oil in their track endeavours. However your initial statement said "BMW M" not "a specific generation of BMW M3", which is exactly what you've just linked to.

BMW has spec'd the 10w-60 lubricant for a variety of M-cars and also the 5w-30 over the years. Currently they are doing the 5w-30 thing again.

Not sure why you've somehow concluded that a company running over-tight rod bearing clearances and subsequently FUBAR'ing an engine means that everything Hi-Po should be running 5w-20....
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Though I also noticed that you didn't comment on my Ford example either
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The reduced oil flow to the engine when cold (please spare me the details of "cold" specification)


No, I think you need to go over those details again because you obviously DON'T get them, as per this next bit:

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is so basic it beats me!


Yes, apparently it does.

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But Based on this graph, the average 5W-30 oil is almost 30 times more viscus at 10C ("cold start") than 100C ("warmed up")
So if I have a positive displacement oil pump and hit the relief at 3500rpm warm, on a 10C cold start if I hit 3500rpm only ~4% of the oil pumped will go through the engine, compared to 100% when warm.


NO!!!!!!

Oh my Lord dude, the relief isn't somebody cracking open the hoover dam and stopping all the water flow through the turbines. It is a SPRING CONTROLLED RELIEF VALVE that REGULATES the pressure the ENGINE sees by RELIEVING (hence the name!) SOME of the pressure by BLEEDING OFF the necessary amount of oil to keep that pressure in check.

I'm not sure how you've come to the conclusion that the relief valve is a 4" pipe that opens like a trap door once a certain pressure is hit but I really don't think this can be explained to you any more clearly than it already has.
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Hopefully going to add some clarity here:

mump_0907_08_z%2Bengine_motor_oil%2Boil_pump_rotor.jpg


This is the inside of a traditional two-gear style Ford oil pump. The section in the lower-left of the picture is where the oil is drawn in from the pan. The section in the top of the picture is where the oil is fed into the engine. On the right-hand side of the pump you can see there is a hole and a valve assembly. This is the relief valve. It is spring-loaded and will begin to crack open once the pressure of the spring is overcome. It is probably wide-open by 65psi with a stock spring.

You'll notice that the relief doesn't dump oil back into the pan, but rather back into the feed side of the pump. This is typical. You'll also notice that the relief isn't very big. Also typical. Its purpose is to regulate the maximum pressure the engine sees, not bypass all the oil the pump moves, so it is literally incapable of bypassing that much volume.
 
Derp! That should have been "gear-style", the SBC is two-gear
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Here's an SBC pump displayed in a similar manner. This is a high performance aftermarket pump with an "enlarged" relief cavity. Though you'll note that it is still tiny relative to the feed/exit holes. It relieves in the same manner as the SBF pump, bypassing the oil back into the feed circuit.

racingoilpump_part.jpg
 
I am sorry bluesubie but I need this last post.

Let's talk about another pump. The human heart! the left ventricle to be specific.
It draws blood from the mitroid valve and pumps it through the aortic valve.
Now the amount of blood in and out is the same (should be obvious) but the size of the valves isn't! The aortic is high pressure (read high speed of blood) as is by definition the bypass valve, but the mitroid is low, sometimes zero pressure (read low speed of blood, and thank gravity for some of the work) and thus bigger so that the same volume can go through it at lower speeds but in a comparable time (that depends on the heart rate). It really is the feeder opening for the right ventricle.

Last the pump doesn't know whether the oil it pumps goes through the bearings or through a tight passage. All it can see is back pressure. It's like a generator powering an 100W light bulb or an 100W computer. It makes no difference to the generator. The calculations you are asking prove you don't understand that.
 
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Originally Posted By: OVERKILL
Oh my Lord dude, the relief isn't somebody cracking open the hoover dam and stopping all the water flow through the turbines. It is a SPRING CONTROLLED RELIEF VALVE that REGULATES the pressure the ENGINE sees by RELIEVING (hence the name!) SOME of the pressure by BLEEDING OFF the necessary amount of oil to keep that pressure in check.

When I was looking through my G's FSM, they were very clear on that point, in fact using the "regulate" terminology, and their test procedure alone makes it pretty darned clear it's not a binary switch.

@nikolas84: First off, the circulatory system is vastly different. As for Shannow's request that you do the calculations and my repetition of that request, and that you think there's a lack of understanding here, I suggest you ask about the academic (and professional) credentials of certain members here.

You brought up the Hagen–Poiseuille equation. When someone brings up an equation to support their position, they had better be able to manipulate that equation. Keep this up, and I'll next ask you to derive it parametrically and show your work.
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Originally Posted By: nickolas84
I am sorry bluesubie but I need this last post.

Let's talk about another pump. The human heart! the left ventricle to be specific.
It draws blood from the mitroid valve and pumps it through the aortic valve.
Now the amount of blood in and out is the same (should be obvious) but the size of the valves isn't! The aortic is high pressure (read high speed of blood) as is by definition the bypass valve, but the mitroid is low, sometimes zero pressure (read low speed of blood, and thank gravity for some of the work) and thus bigger so that the same volume can go through it at lower speeds but in a comparable time (that depends on the heart rate). It really is the feeder opening for the right ventricle.


And in what way does the heart resemble a positive displacement gear pump?
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Last the pump doesn't know whether the oil it pumps goes through the bearings or through a tight passage. All it can see is back pressure. It's like a generator powering an 100W light bulb or an 100W computer. It makes no difference to the generator.


Which is why it isn't feeding both orifices at the same time. The 2nd, much smaller orifice, the relief, has a SPRING LOADED VALVE in it and is simply used to REGULATE the pressure in the main system. I'm not sure how it is possible for you to keep misunderstanding this and then tossing out analogies like we are the ones who don't have a clue here
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The calculations you are asking prove you don't understand that.



Wait, so the guy who designs bearings and lubrication systems for turbines (Shannow) doesn't know what he's talking about, but some guy who doesn't even own a vehicle with an oil pressure gauge or likely has EVER seen the inside of an engine but can quote a textbook math formula is going to teach us all how it REALLY works. Gotcha
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This should be fun.....
 
Originally Posted By: bluesubie
I asked the OP to post his UOA here and I'm sure he would be happier if there was this much discussion and debate about his particular uoa.

Agreed, but I am quite enjoying the ensuing discussion.

This all started when nickolas84 tried to scare away the idea of adding an oil cooler.

Originally Posted By: nickolas84
Definetely do not use an oil cooler. It will reduce lubrication to your engine with the stock oil pump.
 
Originally Posted By: nickolas84
Let's talk about another pump. The human heart!

Although I'm sure it's quite fun, let's not. There's more than enough different pump/valve designs in current use. Why not find details on the EXACT pump used in the vehicle from the title.
 
Good Grief...we have an MD quoting a plastic surgeon, and trying to use flawed analogies of the body to over-rule basic engineering...

Next we'll be improving flow by adding leeches to the sump.

edit...can bring the flow/lube discussion where it was asked before if you like.
 
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Originally Posted By: martinq
This all started when nickolas84 tried to scare away the idea of adding an oil cooler.

His original point was well taken, if you condense it down to something concise, as in, "Don't buy a cheap, non-thermostatically controlled oil cooler."
 
Originally Posted By: Garak
His original point was well taken, if you condense it down to something concise, as in, "Don't buy a cheap, non-thermostatically controlled oil cooler."

Instead of what he said, "Definetely do not use an oil cooler."?

This post is about engine oil and temperature control. There should be discussion about methods to improve cooling and the first step should be to install an oil cooler or assess the cooling systems already in place.
 
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Originally Posted By: martinq
Instead of what he said, "Definetely do not use an oil cooler."?

Bingo. There's nothing wrong with an oil cooler at all, as far as I'm concerned, assuming one buys and installs sensibly.
 
Originally Posted By: bluesubie
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I asked the OP to post his UOA here and I'm sure he would be happier if there was this much discussion and debate about his particular uoa.
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-Dennis


Yeah I jumped off the ship a while ago once I saw equations popping up in the replied and thought I was reading latin.
 
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