Transmission Fluid "redux"

[RobZilla]

I am not trying to bring back any old debates as there are countless threads on this topic. I searched through most of them and don't claim to be knowledgeable at all. In fact the only thing I learned is that my transmission probably has a non recommended fluid in it, and I'm sure I'm not the only one.

Thus the rise of the "Transmission Fluid Redux." I pulled the following product sheets and linked them here for easy reference:

MOBIL 1 SYNTHETIC ATF: Mobil 1 Synthetic ATF

ROYAL PURPLE SYNCROMAX: Royal Purple Manual Transmission Fluid <--- click product sheet

ROYAL PURPLE MAX ATF: Royal Purple Transmission Fluid <--- click product sheet

PENNZOIL SYNCROMESH: http://www.pennzoil.com/documents/Synchromesh Manual Trans Fluid.pdf

CASTROL ATF+4: http://www.castrol.com/liveassets/b...G/local_assets/downloads/p,q/pds_ATFPlus4.pdf

REDLINE SYNTHETIC OIL for transmission - Red Line Synthetic Oil - Gear Oil for Manual Transmissions - MT-90 75W90 GL-4 Gear Oil

MOPAR 75w90 - needs data sheet link

Interestingly enough I could not find Castrol Synorq LT nor a data sheet after a painful search.

I assume that any of the above could be used but I am searching for the best possible option keeping in mind the heat of the Florida summers.

My conclusion:

Based on my research , and as per Tom, our T56's should not be using a GL-5 which is what the Mobil 1 75w90 is. If the Mopar factory fill is the equivalent then wouldn't it be GL-5 also? So one should pick from the above listed options... thoughts.

 

[ROCKET62]

To quote another famous member - the year matters.

 

[RobZilla]

2006. For the purpose of this general discussion let's just assume it's any 96+ T56.

 

[Dom426h]

Add Mopar Synthetic 75W85 Manual Transmission Lubricant to your list as that is what most vipers are running.

Some good info on the allpar site that talks about the diff between GL4/5:
Lubricant for New Venture Gear 3500, 4500, and 5600 Transmissions

 

[LaViper]

At the World of Wheels Car Show in New Orleans,La, I asked the person @ the Tremec Transmission Display what is "The Best" trans. fluid to use in their T56 tranny. He said Mobil 1 Synthetic ATF.

 

[RobZilla]

I am hoping Tom will chime in with his most up to date opinion and info.

 

[RobZilla]

Add Mopar Synthetic 75W85 Manual Transmission Lubricant to your list as that is what most vipers are running.

Some good info on the allpar site that talks about the diff between GL4/5:
Lubricant for New Venture Gear 3500, 4500, and 5600 Transmissions

Cannot find the data sheet online. I was going under the notion that the Mobil 1 75w90 was the same stuff. I could be wrong and the Mopar could be GL-4. That is where the confusion begins.

Good read on that link.

 

[Steve-Indy]

Hi, RobZilla...frustrating that there is so much in doubt with the various tranny fluids lacking CLEAR labeling. Is it an API GL-4 or GL-5??? One should NOT have to go to this much trouble just to find out which is which !!!

One of Tom's old posts said:

"Gear oil isn't just gear oil. For instance API GL-4 is for synchronized transmissions and some differentials, and API GL-5 is for non-synchro transmissions and some differentials. The GL-5 chemistry is much more aggressive and will possibly harm the face of the synchros that act as little clutches to get things to come to the same speed."

Another thread was

http://forums.viperclub.org/rt-10-gts-discussions/629005-transmission-fluid.html

said:


"1) Only use API GL-4 oils in a transmission. GL-5 oils are for differentials and have much different chemistry. Some oils claim both GL-4 and GL-5, but don't use a GL-5 only oil. Same for MT-4 oils; that is for HD no-synchro transmissions.

2) Higher flash point simply means it takes a higher temperature before a lighted flame ignites the vapors over the fluid. It is a telling measurement for fuels and for contaminated oils, doesn't really tell you anything about performance of oils.

3) High viscosity (thicker oil) is why it's hard to shift when cold (not enough friction on the synchros to bring them to same speed quickly). What you want to look for is high viscosity index. This implies it behaves like a thick oil when hot, but behaves like a thin oil when cold. For an engine oil, your first clue is the spread between the two designations; a 0W40 oil is high viscosity index, a 15W40 is lower viscosity index. They both have the same viscosity at 100C, so they are both "SAE 40". An SAE 40 oil must be between 12.5cSt and 16.3 cSt. Unfortunately the gear oil specifications are much wider, so an SAE 90 gear oil can be from 13.5 cSt to 24 cSt. Consequently the difference between a 70W90 and a 75W90 is more esoteric than useful.

Thicker is not automatically better. The Castrol Syntorq is actually a 75W-85W. Yes, two "W" numbers, again because the system for gear oil viscosity was developed before the use of synthetics was popular. Mopar rebrands this oil and calls it a 75W-85. Go figure.

Transmission oils and gear oils (and power steering fluids) are supposed to be changed periodically but for the most part are fill-for-life. OEMs therefore spend their own testing time and money to look at a few candidates and pick one that works. I don't mean to be anti-competitive or poo-poo any brand, but you can't go wrong by choosing an OEM oil. In this case it would be the Mopar oil, or as we know now, the Syntorq or the GM Synthetic Manual Transmission Fluid. OEMs won't allow a factory fill supplier to be the single source, either. That means Castrol has to allow licenses to other manufacturers to produce and sell the fluid also.

I have not looked up the Motul oil, but maybe you can compare the kinematic viscosity at 100C; that is usually provided. Perhaps they also show the KV at 40C; the difference between the viscosity values gives you an idea of the viscosity index. Perhaps the "ideal" oil is one that meets the engine/differential/transmission requirement when hot (typically the KV at 100C) and has as high an index as you can afford. Sort of like the 0W-40 Mobil engine oil concept, if Tremec and Chrysler determine that SAE 85 or 85W is the thickness they need when hot, then look for a 75W-85 or 70W-85 oil."

I vote for CLEAR LABELING...including on the Mopar bottles in my garage!!!

 

[RobZilla]

Thanks Steve. I actually read both of those threads and did some of my own internet searching and came to the same results. Clear labeling would be more than FANTASTIC.

I guess the choice is left up to the individual after carefully considering the options and reference materials.

My choice is either Pennzoil Syncromesh or Pennzoil Synthetic GL-4.

Royal Purple Syncromax would be my on deck choice.

 

[Atppilot]

Gen 3 oil for me:
Redline - 75-90 (MT90) GL4 spec Transmission
Redline - 75W-140 Ultra High Performance GL5 for Rear End. has friction modifiers pre-blended.

 

[RobZilla]

Gen 3 oil for me:
Redline - 75-90 (MT90) GL4 spec Transmission
Redline - 75W-140 Ultra High Performance GL5 for Rear End. has friction modifiers pre-blended.

Excellent!

Data sheet:

Redline Synthetic Oil for transmission - Red Line Synthetic Oil - Gear Oil for Manual Transmissions - MT-90 75W90 GL-4 Gear Oil

Good price too, so I added it to the list. Seems that motorcycle shops carry it in stock. Otherwise it's order online.

 

[fqberful]

AMSOIL MTG is the replacement fluid for GM part #12346190 and Chrysler part #4874459 (Chrysler specification #MS-9070).

If you have an amsoil account it's only $10/qt plus shipping. Works great in the nv4500 trans in that diesel truck too.

I use amsoil stuff in everything. Their quality stands up to the hype as proven by oil analysis.

--FQB

 

[RobZilla]

AMSOIL MTG is the replacement fluid for GM part #12346190 and Chrysler part #4874459 (Chrysler specification #MS-9070).

If you have an amsoil account it's only $10/qt plus shipping. Works great in the nv4500 trans in that diesel truck too.

I use amsoil stuff in everything. Their quality stands up to the hype as proven by oil analysis.

--FQB

Consider it added to the list. Primarily an online order product as well.

AMSOIL MTG - AMSOIL - Synthetic Manual Transmission and Transaxle Gear Lube 75W-90 (MTG) <--- scroll to bottom of page

 

[Tom F&L GoR]

Howdy, all.

For the T-56's that allow the synthetic oil, you will want API GL-4 and NOT GL-5. As mentioned above, GL-5 additive chemistry is what the mouse milk vendors use for parlor games - it makes for spectacular show in wear or friction bench tests, but the chemistry is so aggressive it will corrode the yellow metals in your transmission.

The Castrol product is an unusual 75W-85W viscosity. Mopar relabeled it as 75W-85. In the actual measurement of viscosities, ATFs are around 7 cSt, the Castrol is around 12 cSt, and a 75W-90 will be around 16 cSt at 100C. I don't know that anyone needs to go that thick, but if you think you do, make sure it is GL-4 and synchro compatible (and not GL-5 differential oil.) If the 75W-90 product you buy is GL-4, this still may aggravate cold shifting (and maybe hot shifting.)

Do not ever ever use MT-1 oil. It is for non-synchro transmissions and won't have the friction characteristics needed for shifting.

Summary: I think the sweet spot is a GL-4 oil of 12 cSt.

 

[RobZilla]

Awesome Tom. That was pretty much the last piece of the puzzle.

The recommended 12 cSt... is that @ 100 degrees celcius?

 

[bmw2nv2000]

Other fluids may be better but I can testify the Royal Purple Syncromax made my 06 shift a little smoother especially when cold.

 

[Tom F&L GoR]

Awesome Tom. That was pretty much the last piece of the puzzle.

The recommended 12 cSt... is that @ 100 degrees celcius?

Yes.





I have to add gobble-**** because a three letter reply is too short for the "system."

 

[RobZilla]

Thank you very much Tom!