Do You Like a Gear Oil LV fluid or a Dedicated MTF for manual transmission ?

[zeroptzero]

I have been away from manual transmission cars for a few years now, and I always like to use a dedicated MTF fluid like Amsoil (5w30) MTF , GL4. That fluid always worked great in cold temps, never any issue. I now have a car that suggests a gear oil 75w LV fluid. I always thought that the good dedicated MTF fluids had some friction modifying that worked well with syncros, and I view gear oils as not being as good as an MTF.

75w LV is really thin, like 6 cst range, where the MTF's I used in the past were 9 cst, though we never had issues with cold temp operation.
Maybe I'm overthinking this and it might not mean anything at the end of the day, I just don't know if a gear oil LV is the best fluid to run in a manual 6 speed tranny, my main concern is protection of the syncros , not fuel economy or cold temp operation.

Thanks for any replies.

 

[ammolab]

I have exclusively purchased manual transmission cars since 1964. I used the mfg recommended fluid, gear oil, motor oil and now ATF in my Tremec 6 speed.

I never second guessed the mfg but I will say Redline D4F ATF has been better in my Tremec than the GM fluid.

I’m not sure a fiction modifier is synchro friendly.

 

[SubieRubyRoo]

I have been away from manual transmission cars for a few years now, and I always like to use a dedicated MTF fluid like Amsoil (5w30) MTF , GL4. That fluid always worked great in cold temps, never any issue. I now have a car that suggests a gear oil 75w LV fluid. I always thought that the good dedicated MTF fluids had some friction modifying that worked well with syncros, and I view gear oils as not being as good as an MTF. 75w LV is really thin, like 6 cst range, where the MTF's I used in the past were 9 cst, though we never had issues with told temp operation.

Maybe I'm overthinking this and it might not mean anything at the end of the day, I just don't know if a gear oil LV is the best fluid to run in a manual 6 speed tranny, my main concern is protection of the syncros , not fuel economy or cold temp operation.

Thanks for any replies.

You are likely best-served by reviewing the many MTF posts by @MolaKule, who has formulated many of these fluids, and has offered detailed answers to dozens if not hundreds of MTF questions here.

 

[MolaKule]

I have been away from manual transmission cars for a few years now, and I always like to use a dedicated MTF fluid like Amsoil (5w30) MTF , GL4. That fluid always worked great in cold temps, never any issue. I now have a car that suggests a gear oil 75w LV fluid. I always thought that the good dedicated MTF fluids had some friction modifying that worked well with syncros, and I view gear oils as not being as good as an MTF. 75w LV is really thin, like 6 cst range, where the MTF's I used in the past were 9 cst, though we never had issues with told temp operation.

Maybe I'm overthinking this and it might not mean anything at the end of the day, I just don't know if a gear oil LV is the best fluid to run in a manual 6 speed tranny, my main concern is protection of the syncros , not fuel economy or cold temp operation.

Thanks for any replies.

If you are shy about using the LV you might try MT Life from High Performance Lubricant they call their 75W75 at 7.1 cSt. All of their MTF have been tested in racing applications. The MT Life 75W from HPL is right at 6.0 cSt.

Some use the LV MTF from Redline called MT-LV at 6.3 cSt as a replacement as well.

 

[zeroptzero]

Thanks for the replies on this. I guess I am not shy about using 75w LV fluids, but I am just curious if synchros work best with that type of fluid or with an MTF , I know companies like Redline advertise properties that work better with synchros. I am not sure if that is just advertising lingo, or if synchros work the same with various types of fluids including gear oil.

 

[Overfill]

Thanks for the replies on this. I guess I am not shy about using 75w LV fluids, but I am just curious if synchros work best with that type of fluid or with an MTF , I know companies like Redline advertise properties that work better with synchros. I am not sure if that is just advertising lingo, or if synchros work the same with various types of fluids including gear oil.

75W=LV=6.0cstKV100
synchros work best with synchro-specific friction modifiers. Synchro-specific friction modifiers are only found in MTFs and DCTFs, not generic gear oils nor ATFs. There is a variety of available MTFs with varied kv100 viscosities, not just 6.0cst and 9.0cst : https://bobistheoilguy.com/forums/threads/updated-list-of-dedicated-mtf-fluids.277655/

 

[zeroptzero]

75W=LV=6.0cstKV100
synchros work best with synchro-specific friction modifiers. Synchro-specific friction modifiers are only found in MTFs and DCTFs, not generic gear oils nor ATFs. There is a variety of available MTFs with varied kv100 viscosities, not just 6.0cst and 9.0cst : https://bobistheoilguy.com/forums/threads/updated-list-of-dedicated-mtf-fluids.277655/

That is what I was referring to and my gut feeling, not so much about viscosities but I do want to meet the required specs for my manual transmission. Thank you for the info and reply and link. Much appreciated.

 

[zeroptzero]

After reviewing available products I think Redline MT LV is going to work best for me. That satisfies all of the specs for my Subaru BRZ, and is readily available. I think it is a better choice than gear oil products and perhaps better than the Subaru fluids.

 

[MolaKule]

Thanks for the replies on this. I guess I am not shy about using 75w LV fluids, but I am just curious if synchros work best with that type of fluid or with an MTF , I know companies like Redline advertise properties that work better with synchros. I am not sure if that is just advertising lingo, or if synchros work the same with various types of fluids including gear oil.

What OVERFILL said.

The fluids I suggested to you are ALL dedicated MTF fluids. Dedicated MTF fluids have as a minimum, GL-4 protection ratings, and many nowadays also have GL-4/GL-5 dual protection ratings.

A dedicated or application-specific MTF has special friction modification (FM) chemistry and a hefty Anti-Wear (AW) package.

Other "gear" oils, such as differential lubes or ATFs, do not have the proper FM or AW components and often have viscosities way above or way below dedicated MTF's.

 

[zeroptzero]

What OVERFILL said.

The fluids I suggested to you are ALL dedicated MTF fluids. Dedicated MTF fluids have as a minimum, GL-4 protection ratings, and many nowadays also have GL-4/GL-5 dual protection ratings.

A dedicated or application-specific MTF has special friction modification (FM) chemistry and a hefty Anti-Wear (AW) package.

Other "gear" oils, such as differential lubes or ATFs, do not have the proper FM or AW components and often have viscosities way above or way below dedicated MTF's.

Thank you for the reply on this, that was my initial thought when I started the thread, that a dedicated MTF is going to be best for shift quality and protection, rather than some generic gear oil.

I did not see Redline MT LV on the list , perhaps it was not a dedicated MTF but it has the appropriate viscosity and is friction modified for shift quality of synchro's if I'm reading it right. Would it have friction modifiers and anti-wear package benefits ? if so I am sort of leaning towards it as my preferred transmission fluid choice. I have always liked the Amsoil MTF (5w30) but it is a thicker viscosity than the LV recommendation from the factory.

 

[MolaKule]

Thank you for the reply on this, that was my initial thought when I started the thread, that a dedicated MTF is going to be best for shift quality and protection, rather than some generic gear oil.

I did not see Redline MT LV on the list , perhaps it was not a dedicated MTF but it has the appropriate viscosity and is friction modified for shift quality of synchro's if I'm reading it right. Would it have friction modifiers and anti-wear package benefits ? if so I am sort of leaning towards it as my preferred transmission fluid choice. I have always liked the Amsoil MTF (5w30) but it is a thicker viscosity than the LV recommendation from the factory.

What list, this one? It is at the bottom of the list.
A. These MTL fluids are closest to a Kinematic Viscosity of 6.X cSt@100C (About the same viscosity as Dexron VI ATF) and SAE 70 or so:

1. Castrol Syntrans FE 75W,
2. BMW (Pentosin) MTF-LT-3,
3. Honda MTII or MTF 2.
4. Ford FML-XT-11-QDC
5. Volvo Manual Transmission Fluid (6.4 cSt) [Recommended for: type M655-speed with 6-cyl. engine, M66, MTX75 and MMT6 and of the type M56, M58 and M59 from and including model year 1996. Meets Ford specification WSSM2C200-D2]
7. Redline MT-LV SAE Viscosity Grade 70W/75W Vis 6.5cst@100°C
8. HPL Manual Transmission Life 75W 6.3 cSt
Look at the manf. literature to determine the EXACT description of the product:
https://www.redlineoil.com/mt-lv-70w75w

This list and the others in this forum link ALL contain Dedicated MTF's, so I am not clear as to where your confusion lay.

Thread 'Updated List of MTFs'

May 30, 2024

Updated List of Manual Transmission Fluids May 30th

NOTE: This list is only a “summary” list of MTFs available in the MTF Lubricant Market and only available in US auto parts stores and US Import outlets. It is not an endorsement nor a critique of any one fluid, nor is it implied that any one fluid will cure problems in MTs that have design problems or those that have excessive wear. Viscosities listed are at 100C and rounded up.

A.These MTL fluids are closest to a Kinematic Viscosity of 6.X cSt@100C (About the same viscosity as Dexron VI ATF) and SAE 70 or so:

1. Castrol Syntrans...

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[zeroptzero]

^ Thank you, I think the problem is with my eyes, thanks for reposting it, my mistake. Thanks