Synchromesh Manual Transmission Lubricants

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MolaKule

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White Paper - Synchromesh Manual Transmission Lubricants


Since there has been so much discussion and questions about MTL's, here is a white paper that I hope answers some questions.


Quote:
Most GL5 differential and GL4 Manual Transmission oils contain sulfur-phosphorous EP packages. GL4 does NOT refer to any specific viscosity, but it refers to a level of AW/EP protection for the gearing and bearings in a transmission. GL4-rated oils contain about 40% to 60% of the EP additives that GL5 oils contain.

Both differential and manual transmission fluids use chemical compounds that subdue or inhibit the corrosive effects of sulfur and phosphorous such as calcium, magnesium, boron, potassium or other basic compounds. Emulsifiers, corrosion and rust inhibitors also are included to do their respective jobs.

GL5 differential lubes use friction modifiers to reduce mechanical and fluid friction and add some anti-shudder friction modifier for limited slip, both very different chemical compounds.

Manual Transmission fluids use a different friction modifier for synchro engagement, a modifier that does NOT contain the same Friction Modifier chemicals as differential lubes.

Most manual transmission "specific" fluids (GL4) contain about 40% to 60% of the EP additive of differential lubes (GL5) with inactive or buffered sulphurs. GL4 has come to infer a gear lube with the above percentages of EP additive. The exception of course is ATF fluid used in some of the newer transmissions.

Therefore, both lubes contain the same EP additives, just in different strengths or additive ratios.

Ever since the synchromesh-type fluids appeared on the scene (such as the GM Synchromesh fluid), drivers have had better shifting due to better synchro engagement, attributed to the specialized friction modifier used in these lubes. This specialized friction modifier is better for metallic and composite synchros in terms of shifting and life.

Manual Transmission fluids use a different friction modifier specifically designed for synchro engagement, a modifier that does NOT contain the same chemical compounds as do differential lubes.

A synchromesh fluid usually refers to a specialized fluid that contains special friction modification additives for transmissions that use mechanical synchronizer assemblies; those synchronizer assemblies may be made of carbon fiber composites, sintered metal.

You also have to consider the viscosity of the fluid that the transmission was designed for. The spectrum now ranges from ATF to 75W90 viscosities and therefore a synchromesh GL4 Manual Transmission Lubricant (MTL) can be any viscosity from 7.0 cSt (ATF equivalent viscosity) to a 75W90 type viscosity of approx. 14.5 cSt, and contains special friction modification additives for synchronizer assembly engagement.
brass/bronze, or steel-steel materials.

Current MTL GL4 viscosites are:

1. ATF Series - Type; 6.5 to 8.5 cSt (Equivalent ATF viscosity; Note: ATF additive package is weak compared to most GL 4's)
2. Synchromesh Series -Type; 9.3 - 9.5 cSt (such as Amsoils MTF, Texaco's MTL, Pennzoil's Synchromesh, GM and Chrysler's Synchromesh)
3. 75W85 Series-Type; 9.8 to 11.5 cSt ( Redline's MTL, RP's Synchromax LT, Nissan's MTL, Honda MTL, Castrol Syntorq LT)
4. 75W90 Series-Type; 12.8 to 14.5 cSt (Amsoil's MTG, Redline's MT-90).

MTL specific lubes we're developed for manual tranny's and transaxles, and not for differentials or industrial gear boxes. A differential lube may not kill your tranny, but it is not the optimum lube for it. A diffy 75W90 (GL5) usually has a higher viscosity than does an mtl in the same advertized weight.
 
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Originally Posted By: MolaKule
Note: ATF additive package is weak compared to most GL 4's

Why is that? Do these fluids not require stronger additive packages or is the low viscosity index preventing the introduction of stronger additive packages?

FYI... my car's manual tranny requires an ATF-like fluid, so I'm using RP Synchromax in it...
http://www.royalpurple.com/prod-pdfs/synchromax-ps.pdf
 
White Paper - Synchromesh Manual Transmission Lubricants


Since there has been so much discussion and questions about MTL's, here is a white paper that I hope answers some questions.

Quote:
Synchromesh Manual Transmission lubes we're developed specifically for manual transmissions and transaxles, and not for differentials or industrial gear boxes.

A synchromesh fluid usually refers to a specialized fluid that contains special friction modification additives for transmissions that use mechanical synchronizer assemblies; those synchronizer assemblies may be made of carbon fiber composites, sintered metal, brass/bronze, or steel-steel materials.

Most Differential and Manual Transmission oils contain sulfur-phosphorous EP packages. GL4-rated oils usually contain about 40% to 60% of the amount of Differential lubricant EP’s. Therefore, both MT and Differential lubes contain the same EP additives, just in different strengths or additive ratios.

GL4 does NOT refer to any specific viscosity, but it refers to a level of AW/EP protection for the gearing and bearings in a transmission, so GL4 has come to infer a gear lube with the above percentages of EP additive. The exception of course is ATF fluid used in some of the newer transmissions.

Both differential and manual transmission fluids use chemical compounds that subdue or inhibit the corrosive effects of sulfur and phosphorous such as calcium, magnesium, boron, potassium or other basic compounds. Emulsifiers, corrosion and rust inhibitors also are included to do their respective jobs.

Differential lubes use friction modifiers to reduce mechanical and fluid friction and add some anti-shudder friction modifier for limited slip; both very different chemical compounds.

Manual Transmission fluids use a different friction modifier specifically designed for synchro engagement, a modifier that does NOT contain the same chemical compounds as do differential lubes.

Ever since the synchromesh-type fluids appeared on the scene (such as the GM Synchromesh fluid), drivers have had better shifting due to better synchro engagement, attributed to the specialized friction modifier used in these lubes. This specialized friction modifier is better for metallic and composite synchros in terms of shifting and life.

You also have to consider the viscosity of the fluid that the transmission was designed for. The spectrum now ranges from ATF to 75W90 viscosities and therefore a synchromesh GL4 Manual Transmission Lubricant (MTL) can be any viscosity from 7.0 cSt (ATF equivalent viscosity) to a 75W90 type viscosity of approx. 14.5 cSt, and contains special friction modification additives for synchronizer assembly engagement.

Current MTL GL4 viscosities are:

1. ATF viscosity Series; 6.5 to 8.5 cSt (Equivalent ATF viscosity; Note: ATF additive package is weak compared to most GL4's)

2. Synchromesh viscosity Series; 9.3 - 9.6 cSt (such as Amsoils MTF, Texaco's MTL, Pennzoil's Synchromesh, GM and Chrysler's Synchromesh)

3. 75W85 viscosity Series; 9.8 to 11.5 cSt ( Redline's MTL, RP's Synchromax LT, Nissan's MTL, Honda MTL, Castrol Syntorq LT)

4. 75W90 viscosity Series; 12.8 to 14.5 cSt (Amsoil's MTG, Redline's MT-90).

A differential lube may not kill your manual transmission in your light truck or car, but it is not the optimum lube for it. A differential 75W90 (GL5) lubricant usually has a higher viscosity than does an mtl in the same advertised weight.

Many if not most GL5 fluids rated for differentials may also be rated as MT-1. Some manufacturers, such as Amsoil®, state the following:

“Recommended for use in differentials, manual transmissions and other gear applications requiring any of the following specifications: API GL-5, MT-1, MIL-PRF-2105E, Dana SHAES 234 (Formerly Eaton PS-037), Mack GO-J, or the differential (hypoid) gear oil specifications from all domestic and foreign manufacturers such as GM, Ford and Daimler Chrysler. Can also be used in axles where an API GL-4 lubricant is recommended.”

This MT-1 rating refers to use in heavy duty truck transmissions, and as such, does NOT necessarily mean that this fluid will function properly in a light truck or car synchromesh transmission.
 
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Quote:
Note: ATF additive package is weak compared to most GL 4's

Why is that? Do these fluids not require stronger additive packages or is the low viscosity index preventing the introduction of stronger additive packages?


ATF fluids contain a specific additive package for Automatic Transmissions, and not for manual transmissions. Most ATF specifications for use in mtl's, IMHO, were to improve cold weather shifting, and not to improve wear.

Look at the VOA's for clean ATF fluids and compare to clean MTL analysis for example. There is a big difference in the AW/EP additive levels between the two.

ATF's contain AW's, whereas mtl's and differential lubes contain
both AW's and EP agents.

Viscosity and Viscosity Indexes are two different animals.
 
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so an atf viscosity series should work well in a np231? chain driven transfer case no clutches or anything just a pump. If so who makes a low visc syncromesh mtl? thanx mola
 
Many transfer cases do use ATF, while some like Toyota, use a 75W90 weight lubricant.

As of right now, I cannot recommend any 7.0 cSt lubricant for an mtl.
 
yea its spec'd atf, after reading this i was thinking about putting in some mtl. so no one makes that visc or? would penz be to thick?
 
Originally Posted By: MolaKule
Many transfer cases do use ATF, while some like Toyota, use a 75W90 weight lubricant.

As of right now, I cannot recommend any 7.0 cSt lubricant for an mtl.


Anything wrong with Royal Purple's Synchromax? I'm currently running it in my atf spec'ed mtx as it's the only one I could find in an atf visc. (7.7cst)

Is there as much of a benefit to running an mtl in an atf spec'ed transfer case as there is to running an mtl in a mtx if the t-case has no synchros? An atf wouldn't provide the EP qualities that I assume would be good for a t-case. Would normal engine oil be any better than atf?
 
I dumped my ATF for some RP synchromax the other day no noticeable differences yet. NP242 (T/C)
 
Originally Posted By: Taylor
I dumped my ATF for some RP synchromax the other day no noticeable differences yet. NP242 (T/C)



I have 178k on my 04.5 with the NP271...been running synchromax since 50k...actually shifts better than with ATF. My NV5600 hates the thinner Synchromax, and responds best to Redline MTL.

I believe the older bottles of Synchromax indicated you could run it in place of ATF in manual gearboxes and transfercases.
 
With a mechanical xfer case requiring atf, a quality mtf/mtl can only be an improvement. With the amount of wear that I've seen in some xfer cases, I just don't understand why an ATF was required, MPG or wear?

How soon we forget? One of the original MTFs was the BG syncroshift. Torco also has an MTF.
 
Don't forget that Autotrac was the bandaid for the shudder caused by DexronIII, which is what those TC's were original filled with.

Concerning versatrac, I haven't seen any in the shop. But, since most are under warranty, I expect that most failures will be cared for by the dealer.

BTW, a real TC, IMO, doesn't use clutches. I'll take a gear'd xfer case with mechanical manually shifting any time. And, ALL that I've seen that failed were usually lubed related failures, that can be prevented.
 
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