Lexus Toyota "Lifetime ATF" - baloney

Those charts are obsolete because they assume first generation-type Dex/Merc fluids and do not consider fluids with the later, enhanced additive and base oil chemistry.
I guess the miracle fluids will change the chemistry of the older transmission gaskets too, and they won't break down under temperature.

I highly suggest you study the basic equations of viscous fluid flow
I probably know more than you do. I don't need to prove anything online, I have my PE.

You won't accept that pressure drop on any restrictions (around valves, in orifices, even pipes) is directly related to VISCOSITY of the fluid.
Probably you'll tell that to Stokes too, that viscosity doesn't matter: https://en.wikipedia.org/wiki/Stokes'_law

I'm done teaching you for free. Wikipedia can't even probably help you... Oh, look at the Re number, what's there? A miu? Neah, it can't be because viscosity doesn't matter....

Moody_EN.svg
 
Yep I don’t agree with the lifetime fluid junk they try to claim. It’s ridiculous I’d still have dipsticks if it was my decision. Transmission services are the way to go.
Yeah, i find every car brand ridiculous not having serviceable transmissions, especially volkswagen.
 
I guess the miracle fluids will change the chemistry of the older transmission gaskets too, and they won't break down under temperature.


I probably know more than you do. I don't need to prove anything online, I have my PE.

You won't accept that pressure drop on any restrictions (around valves, in orifices, even pipes) is directly related to VISCOSITY of the fluid.
Probably you'll tell that to Stokes too, that viscosity doesn't matter: https://en.wikipedia.org/wiki/Stokes'_law

I'm done teaching you for free. Wikipedia can't even probably help you... Oh, look at the Re number, what's there? A miu? Neah, it can't be because viscosity doesn't matter....

Moody_EN.svg
Ouch. Stick around a while, read some of molecule’s posts. While certainly he cant be perfect, he is in industry. Attacking a guy with his track record of experience (looking before you leap) doesn't help our perception of your own credibility.

internet posts are hard.
 
I am not attacking nobody, he attacked me.
And while he might be a guru in chemistry, he certainly doesn't understand fluid flow like I do.
I didn't tell him to go read a chemistry book...
 
I am not attacking nobody, he attacked me.
And while he might be a guru in chemistry, he certainly doesn't understand fluid flow like I do.
Molekule did not attack you. Furthermore, before you tell everyone how much you know and how little Molekule knows about fluid dynamics, you ought to spend some time reading his posts and learning what his track record is, else you risk making yourself look even more like a fool.
 
I guess the miracle fluids will change the chemistry of the older transmission gaskets too, and they won't break down under temperature...
What's a slippery fluid? What is the change in internal pressure of the AT when the viscosity of the ATF is reduced.

You still haven't answered any of the questions I posed and now you bring up more side issues!

I do not know what miracle fluids you have referred to, but the "seal" compatibility between the older Dex/Merc fluids and the newer fluids was never an issue. There is a difference between gaskets and seals. When we speak of seals we are usually referring to those elastomers that keep fluids from seeping or leaking from around rotating shafts, such as for example, crankshafts and transmission input and output shafts.

Mola said:
When Dexron VI was introduced GM stated it could be used in any of their Automatic Transmissions, that is, it was back-speced, so apparently GM drivetrain engineers had tested Dexron VI in the older, loosey-goosey transmissions of yore and found no pressure problems with its use.
 
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...You won't accept that pressure drop on any restrictions (around valves, in orifices, even pipes) is directly related to VISCOSITY of the fluid...
I have never denied anything, which I why suggested you further study the basic equations of viscous fluid flow, because due to some of your prior responses, it appeared you had only superficial knowledge about AT fluid mechanics, and this would help you further understand the topic.

Posting charts from the internet does not necessarily mean one understands the physics behind it all.

The Reynolds number is basically a ratio of inertial forces to viscous forces. The Reynolds equation helps one to determine when laminar or turbulent flows occur, and where there might be a transition from laminar to turbulent flow and vice versa.

One of the better introductory texts available on fluid mechanics is the one by Fox and McDonald (Purdue University), Introduction to Fluid Mechanics, John Wiley and Sons. Chapter 8 has some excellent discussions and graphs on incompressible viscous fluid flow.
 
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I have never denied anything
You basically stated that a pump creates STATIC PRESSURE.

That's false at a fundamental level. To my knowledge a pump creates fluid flow. Kinetic energy, dynamic pressure if you want to call it that way.
The restrictions in the circuit create the static pressure, by converting that dynamic energy. Restrictions that are dependent on fluid friction, viscosity.
Open pumps have zero pressure at their output.

This is such a fundamental thing... that we can't have a conversation.

Especially if you keep suggesting that I need to read books that I ALREADY had, part of my professional training.

Molekule did not attack you.
He did and keeps doing it in a passive aggressive mode. "Go and read a book" is attack at person (that means "You are stupid"), instead of discussing the ideas. I am presenting physics fundamentals and he is presenting... reactions.
You don't know my education (I have a M.Sc. and a P.E) and it should be irrelevant in a discussion. Facts should be the only thing that matters.

However, if only one person is allowed to post here, I'm fine with that too.
End of discussion.
 
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He did and keeps doing it in a passive aggressive mode. "Go and read a book" is attack at person (that means "You are stupid"), instead of discussing the ideas. I am presenting physics fundamentals and he is presenting... reactions.
You don't know my education (I have a M.Sc. and a P.E) and it should be irrelevant in a discussion. Facts should be the only thing that matters.

However, if only one person is allowed to post here, I'm fine with that too.
End of discussion.
You need to grow up. Even if you are correct about some things people may stop listening.
 
You basically stated that a pump creates STATIC PRESSURE.

That's false at a fundamental level. To my knowledge a pump creates fluid flow. Kinetic energy, dynamic pressure if you want to call it that way.
The restrictions in the circuit create the static pressure, by converting that dynamic energy. Restrictions that are dependent on fluid friction, viscosity.
Open pumps have zero pressure at their output.

This is such a fundamental thing... that we can't have a conversation.

Especially if you keep suggesting that I need to read books that I ALREADY had, part of my professional training.


He did and keeps doing it in a passive aggressive mode. "Go and read a book" is attack at person (that means "You are stupid"), instead of discussing the ideas. I am presenting physics fundamentals and he is presenting... reactions.
You don't know my education (I have a M.Sc. and a P.E) and it should be irrelevant in a discussion. Facts should be the only thing that matters.

However, if only one person is allowed to post here, I'm fine with that too.
End of discussion.
Mola said:
What's a slippery fluid?

What is the change in internal pressure of the AT when the viscosity of the ATF is reduced.

You still haven't answered any of the questions I posed and yet you continue to bring up side issues!

What I stated below was in the context of a complete, closed (bounded) hydraulic system, not in terms of isolated components, which I think most people understood.
Mola said:
Anyone who has investigated AT hydraulic systems knows it is the pump that creates hydraulic pressure, but that is not the question. The question was/is: If a lower viscosity fluid of the same volume is placed inside the AT, what will be the pressure change within the original transmission in question?

We're discussing the source of fluid flow and pressures in a complete, bounded hydraulic system. In a hydraulic SYSTEM, the mechanical energy applied to the pump is converted to mass fluid flow, or fluid inertia. Any resistance to the fluid from restrictions encountered in the system such as valves, regulators, filters, piping, etc., results in pressure differentials at various points in the system.

Without a source to 'move' this fluid mass, no pressure differentials can occur in a bounded hydraulic system. The mechanical energy conversion that occurs at the fluid pump becomes the source of system pressure. Therefore, the pump in any hydraulic system, bounded by internal fluid restrictions, becomes the source of system pressure.

Without the pump, no internal fluid flow, no system pressure can occur to operate actuators.
 
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My original statement was that in this SYSTEM, the viscosity plays a huge role. You deviated the discussion to the pump, like the pressure will be independent of the fluid viscosity. And you pointed to the pressure regulating valves that will maintain that pressure the same.
I disagree. Viscosity matters hugely.
Those valves and orifices are mechanically calibrated (designed) for a certain viscosity of the fluid. Flowing a fluid with a different viscosity, will result in different set points for all the elements inside valve body.
It's really simple fluid mechanics.
 
You deviated the discussion to the pump, like the pressure will be independent of the fluid viscosity. And you pointed to the pressure regulating valves that will maintain that pressure the same.
I never deviated from the discussion and never did state pressures were independent of fluid viscosity, otherwise I would not have mentioned incompressible viscous flow for further study, Post #79, which contains a viscosity variable or coefficient.
I disagree. Viscosity matters hugely.
Then by now you should be able to answer the question originally posed to you: If a lower viscosity fluid of 5.5 cSt@100C of the same volume is replaced inside the AT, which formerly had a 7.5@100C cSt ATF fluid of the same volume, what will be the pressure change and the measured pressure at Point "R" within the transmission in question, AFTER the lower viscosity fluid has replaced the higher viscosity fluid?

The transmission was tapped at a specific point (point "R") just past (post) the pressure regulator, and the original pressure was measured to be 150 psi with the 7.5@100C cSt ATF.

A constant and specific engine RPM at a constant and specific gear ratio with a constant load was maintained for both fluids. The transmission fluid temperature is maintained at 100C while in the load test cell for both fluid viscosities.

So here is your opportunity to answer a simple AT hydraulic question without throwing strawmen into the discussion.
 
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Molekule did not attack you. Furthermore, before you tell everyone how much you know and how little Molekule knows about fluid dynamics, you ought to spend some time reading his posts and learning what his track record is, else you risk making yourself look even more like a fool.


^^^^^^^^^^↑^^^^^^^^^^^^

Exactly.... Molakule knows far, far, far, far, far more than you, me and likely 98%+ everyone else on here about oils, viscosity, additives, pumps, ATFs or CVTs, spark plugs, and quite a bit of other extremely deep scientific subject matter.
 
The transmission was tapped at a specific point (point "R") just passed (post) the pressure regulator,
So it doesn't matter, you can fill it with water at 150 psi and transmission will run?
Actually go with compressed air at 150 psi, because that's all it matters... static pressure.

This is beyond ridiculous, I'm out.
 
So it doesn't matter, you can fill it with water at 150 psi and transmission will run?
Actually go with compressed air at 150 psi, because that's all it matters... static pressure.

This is beyond ridiculous, I'm out.
Good.

Because it’s clear that you can’t answer the question.

I can’t either, but Molakule can.

Perhaps you should listen to the expert, instead of listing your degrees.
 
P. E degree... Like Phys Ed.... Aka a gym teacher...

Nothing wrong with that by the way. We need PE in schools more now than ever before.

That world champion wanted to say that coefficient of traction in regards to CVT fluid did not exist. . . Or that regular ATF did not operate upon coefficient of friction. Which is totally contrary to reality and how those fluids actually work in those different type of transmissions. Then argue with someone who has an enormous amount of knowledge and expertise in actually formulating those fluids for those types of transmissions.
 
Fractional being 21%.
So... possible reduced pressure on internal clutches/bands is no biggie? Because we have a strong fluid that protects the metallic gears?
My post was about people using LV in transmissions that were not designed for that.

Viscosity is very important in a transmission that works using that viscosity to create pressure differentials inside the valve body.
The answer to the question was given in post #73 with an added link to

https://www.sonnax.com/tech_resourc...t-i-main-pressure-regulator-valve-line-upsand

which gave an explanation as to pressure regulation and which I thought was a good explanation.

The pressure regulator acts as a variable "constriction" device (with a variable orifice) which serves to maintain pressure under variables such as engine rpm (and of course pump rpm), and pressure demands for the torque converter and clutch actuators. So the pressure regulators provide the necessary and variable resistance to fluid flow to maintain the needed pressure.

In older transmissions, the 'spring rate' of the spring in the pressure regulator body modulated the fluid flow in an attempt to maintain the needed pressure. When GM tested the lower viscosity fluids in older transmissions, they found that the pump volume, pump flow rate, and spring rate was sufficient to accommodate them, which is why they back-speced the Dexron VI fluid to those older transmissions.

In addition to the main pressure regulator, in the TH400 for example, the governor played a major role in determining the automatic shift points for this transmission. That governor was an additional pressure valve with centrifugal flyweights and springs with outer (primary) and inner (secondary) weights, two each, and two springs.

In modern transmissions, a solenoid in the valve (with possibly an additional spring) will modulate the orifices to maintain pressure. The solenoid valve is controlled by the ECM with inputs to the ECM, for example, from the TPS, engine rpm, wheel speed rpm, pressure sensors, and or rpm sensors that monitor transmission input/output shaft rpms, or even the input clutch drum rpm.

So under the constraint conditions imposed in post #93, the pressure of either fluid would be maintained at 150 psi.
AT Pressure Regulator.jpg
 
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One of the better introductory texts available on fluid mechanics is the one by Fox and McDonald (Purdue University), Introduction to Fluid Mechanics, John Wiley and Sons. Chapter 8 has some excellent discussions and graphs on incompressible viscous fluid flow.
I agree with your posts and I'm not adding to the conversation because a few individuals are triggered. I will say this ... I took classes from Fox, McDonald, DeWitt, Viskanta, Hoffmann, and others. All of them were outstanding instructors. McDonald completely filled backboards on two sides of the room with perfect handwriting, never making an error. He kept talking as he erased it all and then filled the backboards again with sketches, equations and sentences that were aesthetically pleasing to view. I often wondered if he wrote from photographic mental imagery. Those were the best years of my education ~45 years ago.
 
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