Who has used a high viscosity transmission fluid in a LV application?

I was wondering this too, many people advocate for a thicker oil, but not a thicker ATF. A thinner ATF is for fuel savings, so why not a thicker ATF?

Maybe it is because an oil goes through tougher conditions.
ATF is basically a hydraulic fluid that also doubles as a lubricant. Changing the viscosity would change the pressure of the fluid, which could theoretically cause the trans to misbehave. It's also true ATF is not subjected to the extremes of engine oil. Most of the parts in an engine rely on hydrodynamic lubrication under extreme temperatures and speeds. Transmissions also do not operate at the same temperatures of an engine. A transmission that was operating at 212°F-400°F (common temperatures in the cylinders and rings) would fail rather quickly.
 
ATF is basically a hydraulic fluid that also doubles as a lubricant. Changing the viscosity would change the pressure of the fluid, which could theoretically cause the trans to misbehave...

Somewhere here on BITOG I calculated the pressure change due to a viscosity change using a constant orifice size and pump volume-flow rate and the pressure change was miniscule. AT Transmissions have ample pump flow rates and the internal pressures are maintained by pressure regulators.

If a slight drop in viscosity would have been causing marginal pressures and erratic transmission operation, then we would have seen older back-speced fluid transmission problems, which we haven't seen.
 
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Those AISIN transmissions were originally designed for T4. WS is "working", but IMO that's just because the original pumps had enough head capacity to drop from.
The pump pressure regulator takes care of maintaining the right pressure if it tends to be too high, by dumping more fluid back in the pan. It just cannot "add" pressure if is too low.
On other hand, thicker fluid might just warm up more, due to increased losses, ending up with the same operational viscosity.
The best thing to do is cool that fluid. Even if is "LV", cooled just 10F might bring it's viscosity in line with what the non-LV has at 10F higher.
what is T4 Cst?
 
Depending on the Blender, the Toyota T-IV (JWS3309) 100C viscosity will range between 7.1 cSt to 7.3 cSt; 40C viscosity is 33 cSt. There has never been a Toyota T4 ATF.

Historically, there have been Toyota T, T-II, and T-III ATFs.
Thanks for the information, the atf I am using in my jetta is the castrol universal atf/cvt snake oil, which is around 7.3 cSt, just checking to make sure it will work in the long run.
 
Thanks for the information, the atf I am using in my jetta is the castrol universal atf/cvt snake oil, which is around 7.3 cSt, just checking to make sure it will work in the long run.
Why is it snake oil? Read Mola's other statements where he said that Transmissions can tolerate a wider variance it viscosity.
 
Why is it snake oil? Read Mola's other statements where he said that Transmissions can tolerate a wider variance it viscosity.
I don't trust running this stuff in a CVT, at the same time castrol doesn't just claim something.
 
...at the same time castrol doesn't just claim something.
True, and it's not a matter of viscosity, but of friction modification. Afton claims it has developed a DI package that contains friction modification chemistry such that it can function in both Step-Shift and CVT AT's.

Step-shift ATs and CVTs have different dynamic friction requirements. No chemistry is predictive nor does it contain any artificial intelligence, so how does this DI package determine if it is being used in a Step-Shift or CVT?

I am not saying that this product is anything but what they say it is; I am simply skeptical.
 
You all realize that contemporary transmissions have fluid temp sensors, right? Viscosity is a VERY important parameter in transmission performance. The transmission control module uses fluid temperature in its shift calculations.
Some people seem to think that “transmissions can operate on a wide range fluid viscosity”, so it doesn’t matter if you use a fluid that’s thicker from the manufacturers approval. This is very misguided information.

Yes, transmissions can operate on a wide range of viscosity, otherwise transmissions wouldn’t operate correctly with cold fluid, or hot fluid because the viscosity is vastly different when cold vs hot. However, what many fail to realize is the transmission control module has logic coded in the programming that alters shift timing/characteristics based on fluid temperature. Anyone want to guess what fluid viscosity that OE computer module programming is based off of? If you guess the OE fluid then you are right (obviously). Fluid temperature affects the viscosity, and the viscosity affects the pressures needed to complete proper shifts. Use the wrong viscosity fluid and the transmission control module *may* notice shift inconsistencies at certain temperatures, resulting in altered shift feel/characteristics.

Transmission shift calculations are that precise to notice difference in viscosity.
 
True, and it's not a matter of viscosity, but of friction modification. Afton claims it has developed a DI package that contains friction modification chemistry such that it can function in both Step-Shift and CVT AT's.

Step-shift ATs and CVTs have different dynamic friction requirements. No chemistry is predictive nor does it contain any artificial intelligence, so how does this DI package determine if it is being used in a Step-Shift or CVT?

I am not saying that this product is anything but what they say it is; I am simply skeptical.
Yes I am skeptical too of running it in a cvt due to the major differences.
 
I run redline d4 in my hyundai sonata 2.0t 6 speed that calls for hyundai sp4m which is a d6 viscosity. I run a bottle of lube gard red in it. Cooler line flush evey 40k miles. Runs great. 122k on car.
 
The modern LV and ULV fluids are more viscosity stable than the older 7.5cSt fluids of yore,
what if i use modern additive from aftermarket fluid company

my transmision requires viscosity of 5.8 @100c , i would like to use 7.4 @100c

like what the transmission manufacturer suggest




 
what if i use modern additive from aftermarket fluid company

my transmision requires viscosity of 5.8 @100c , i would like to use 7.4 @100c

like what the transmission manufacturer suggest





I believe I have read that Castrol Import Transmax has a 7.4 @100c viscosity. It is a multi fluid but is marketed as meeting Dex3/Merc fluid.

Or even 8, as per ASTM D-445.

 
To answer the thread starter's question; Yes, and I'm not using any of the "vintage"ATFs. I look for the "HDs" that are suitable or approved for Allison's 995 or 668.
 
You don't need any aftermarket additives if you change fluid periodically.

OK, but why? The newer LV and ULV fluids are much more stable than any of the vintage ATF's.
i mean since i live in dry environment with an average of 72F in winter and 109.4 F in summer, my average transmission fluid temperature (TFT) is 194 f ,

i would like to try newly released atf from high quality aftermarket company like : redline d4 , amsoil multi vehicle ATF ,petro canada duradrive mv , Wolf Vitaltech Multivehicle ATF , Liqui Moly ATF Top Tec 1200 .... etc , these are more than 6.9 @100c viscosity and aren't vintage


instead of low viscosity mazda fz that has 5.8 @100 .

and i know one person who has aisin fw6ael and used mercon atf
1656602540770.png
instead of mazda fz for19k miles and didnt noticed any diffrence

another person who has aisin fw6ael and instead of mazda fz he used pure guard global atf with 7 @100c of viscosity for 1000 miles with smooth shifting .

how to determine if the fluid isnt suitable other than used oil analysis ?
 
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i mean since i live in dry environment with an average of 72F in winter and 109.4 F in summer, my average transmission temperature is 194 f ,

i would like to try newly released atf from high quality aftermarket company like : redline d4 , amsoil multi vehicle ATF ,petro canada duradrive mv , Wolf Vitaltech Multivehicle ATF , Liqui Moly ATF Top Tec 1200 .... etc , these are more than 6.9 @100c viscosity and aren't vintage


instead of low viscosity mazda fz that has 5.8 @100 .

and i know one person who has aisin fw6ael and used mercon atf View attachment 105933 instead of mazda fz for19k miles and didnt noticed any diffrence

another person who has aisin fw6ael and instead of mazda fz he used pure guard global atf with 7 @100c of viscosity for 1000 miles with smooth shifting .

how to determine if the fluid isnt suitable other than used oil analysis ?
I've been using the Pet-Can MV Duradrive in everything since the product came out. I'll switch to their 668 next time.
I have an unopened pail of the Chevron HD example to use up first.
My usage is about a 5 gallon pail a year, so I'm not a big customer..

edit; IMO low vis ATFs, gear oil and engine oils are for fuel economy.
 
I've been using the Pet-Can MV Duradrive in everything since the product came out. I'll switch to their 668 next time.
I have an unopened pail of the Chevron HD example to use up first.
My usage is about a 5 gallon pail a year, so I'm not a big customer..

edit; IMO low vis ATFs, gear oil and engine oils are for fuel economy.
Give us the name and make and model of each cars
 
Allisons with electronic controls designed in the 1990s were fully able to function properly on PAO based 0W20 (then called "arctic" engine oil), petroleum based15W40 ("normal" engine oil) and Dexron III. I'd be surprised if any transmission designed in the last 10 years would have a problem with different grades of ATF. Adaptive algorithms look at speeds to determine slip time and the solenoid commands are adjusted accordingly to produce the desired profile.
 
Adaptive algorithms have limits to worry about.... especially with certain auto brands that try to build the failure in if their specific fluid isn't used.

I run full viscosity full synthetic multivehicle ATF in my Toyota that requires LV WS. I am in a typically warm climate. The brookfield -40F numbers, OE WS ~8000, are close enough to the full visc universal ATF in case I go to a cold climate for a ski trip. The transmission functions perfectly and definitely less noisy/clunky. I figure the ATF will shear some and still be thicker without being too thick. I have 3 drain/refills on the thick stuff so the percentage is high enough to draw a conclusion with my specific transmission and weather. The transmission hasn't misbehaved.

The problem is that one's experience isn't for all. For your transmission, it will be trial and error. Feel free to test with a single drain/refill. If you have no issues, so be it. If something acts up, you'll have to exchange all the fluid. If it works fine, then you can consider an additional drain/refill to increase the percentage of thicker ATF, or alternate for a half-way blend. Price the replacement transmission. If there is any material or programming incompatibility, you might wear it out rapidly and need a replacement. That is the risk you take when you use non-OE recommendations.

 
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