best non-synchronized manual trans oil, low-vis

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diesoiluser

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Looking for a ~10 cSt @ 100°C lubricant or for a gearbox without synchronizers. High lubricity is the goal, cost is no object. What is the best?

Long change interval would be nice but not necessary. Anti-wear, anti-scuff performance is required but not extraordinary. Shear rates are lower than a hypoid gear but higher than an engine. Oil will be filtered and cooled to 100-120°C. High VI would be nice but not necessary. There are no copper-containing components exposed to the lube.

For convenience, 10 cSt is SAE J300 30 grade, or SAE J306 high 80 low 85 grade.

So far I found CAT (Caterpillar) TDTO SAE 30, but it appears not to be synthetic. I would think full synthetic would perform better but I don't see an equivalent with the desired viscosity.
 
Hi !

I don't know if it would help, but I found these 3 full syn trans oils on Q8oils website, since it's a brand I'm familiar with, and I already bought some Ntech 75W-80 to convert my gearbox (JH3) to full syn :

Q8 T 60 Ntech 75W-80
Q8 SuperGear V 75W-80
Q8 SuperGear S 75W-80

go get the TDS @ www.q8oils.com
smile.gif
I don't know if Q8 is already on the USA market : https://www.q8oils.com/EN/Mainnavigation...-agreement.aspx
 
From the Amsoil candidate listed above:
"Their non-slip friction properties are designed to prevent
clutch slippage"

Sounds like lubricity is compromised to accommodate friction elements like clutches. Is there a better one that has no friction modifiers that increase friction? I need friction modifiers that decrease friction.

Again, my system has no synchronizers, clutches, or any elements that require increased friction.
 
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I found Red Line MTL 75W80 GL-4 Gear Oil, but again the blurb indicates it contains friction modifiers for synchronizers. To me that means the lubricity would not be as good as it could be.
 
Originally Posted By: diesoiluser
I found Red Line MTL 75W80 GL-4 Gear Oil, but again the blurb indicates it contains friction modifiers for synchronizers. To me that means the lubricity would not be as good as it could be.


You need to define lubricity.

Whether the oil has a friction modifier or not, it doesn't affect the film strength or the EP protection.

The major consideration here would be the proper viscosity and EP protection.

The Amsoil PowerShift or similar should meet your needs.
 
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Originally Posted By: diesoiluser
From the Amsoil candidate listed above:
"Their non-slip friction properties are designed to prevent
clutch slippage"

Sounds like lubricity is compromised to accommodate friction elements like clutches. Is there a better one that has no friction modifiers that increase friction? I need friction modifiers that decrease friction.

Again, my system has no synchronizers, clutches, or any elements that require increased friction.


Of course any Caterpillar TO-4 product is going to include a blurb about frictional characteristics -- that doesn't mean that you're sacrificing any, as you put it, lubricity.
 
Originally Posted By: MolaKule
You need to define lubricity.

Friction coefficient in the boundary lubrication condition (solid-on-solid).

It's my understanding one thing friction modifiers that accommodate clutches, synchros, etc. do is intentionally increase the boundary friction coefficient to avoid slippage. I am primarily after fuel economy of the engine that is attached to my box, so that is opposite the goal. I understand the FMs are not intended to maximize friction, but still I don't want to leave anything on the table.

From there I need the lowest viscosity that will provide adequate film thickness at the tooth and bearing contact pressures involved. The answer there is 10 cSt at 100°C, based on empirical tests we have run already and recognizing the difference between the absolute viscosity requirement and a kinematic viscosity measurement/specification.
 
Originally Posted By: Ramblejam
Of course any Caterpillar TO-4 product is going to include a blurb about frictional characteristics -- that doesn't mean that you're sacrificing any, as you put it, lubricity.
Sorry, I don't understand your comment. The CAT blurb did not indicate friction modifiers, the Amsoil one did.
 
Originally Posted By: Superflan

Q8 T 60 Ntech 75W-80
Q8 SuperGear V 75W-80
Q8 SuperGear S 75W-80
www.q8oils.com
Nice. I will look through all of those.
 
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On second thought "solid-on-solid" is probably not quite right. What I mean is the effective friction coefficient in the

solid-tribofilm-solid, or
solid-whatever;additive;keeps;surfaces;apart;from;each;other;at;the;molecular;level-solid

condition.
 
Originally Posted By: Greasymechtech
What transmission, sump size, application, engine, vehicle, purpose?

New-design transmission already in prototype stage and under development. We (reluctantly) took over the design from someone else. I've been nominated as the lube guy, hence me being out here on BITOG asking questions.
Sump as big as required.
Heavy-duty on-road truck.
Turbo diesel engine.
Severe service.

None of these specify the fluid. Can you tell me where your questions are leading? I don't understand.
 
Originally Posted By: diesoiluser
Sorry, I don't understand your comment. The CAT blurb did not indicate friction modifiers, the Amsoil one did.

Caterpillar TO-4 is merely a fluid specification that deals with, among other things, clutches and wet brakes - accordingly, any product that carries this approval will likely mention frictional characteristics in marketing/data sheets.

I still stand by my initial recommendation made in the 1st post of this thread. Contact Pablo: http://www.oilslubesfilters.com/
 
Originally Posted By: diesoiluser
Originally Posted By: MolaKule
You need to define lubricity.

Friction coefficient in the boundary lubrication condition (solid-on-solid).

It's my understanding one thing friction modifiers that accommodate clutches, synchros, etc. do is intentionally increase the boundary friction coefficient to avoid slippage. I am primarily after fuel economy of the engine that is attached to my box, so that is opposite the goal. I understand the FMs are not intended to maximize friction, but still I don't want to leave anything on the table.


I didn't ask anyone to define Friction, but lubricity.

Lubricity is the measure of the reduction in friction and or wear by a lubricant. The study of lubrication and wear mechanisms is called tribology.


While lubricity has been used in the past it is an archaic term and not very descriptive.

FLuid film thickness is based upon things such as pressures, HP/torque encountered, gear/tooth profiles, bearing and shaft size, rpm and temperature, so min viscosity is important.

Quote:
Sounds like lubricity is compromised to accommodate friction elements like clutches.



I really don't see how anyone could make that assumption.

Originally Posted By: Greasymechtech
What transmission, sump size, application, engine, vehicle, purpose?


A valid question since engine size/torque/HP is going to determine bearing size, gear and shaft diameter, and the lubricant needed.
 
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