Best fluid for 3 different manual transmissions?

[Yuk]

I want to buy enough manual transmission fluid to care for 3 different cars:

1991 Nissan Sentra - GL-4
1999 Volkswagen Passat - GL-4 (many have written that this transmission is absolutely incompatible with GL-5)
2007 Mazda 6 - GL-4 or 5

I'm most concerned about the VW. I have frequently read on VW sites that a 50/50 mix of redline mtl and mt-90 works well.

What do you guys think will be the best fluid for these three cars. BTW, cold weather performance is extremely important where I live.

 

[Pablo]

There is more to life than GL ratings, what vis is required and what vis are you shooting for in each one?

 

[Yuk]

The Nissan manual does not spec. a viscosity, only specifies GL-4.

VW manual says it's a sealed box, with a lifetime fill...

, but many owners suggest 75W-90.

The Mazda manual says 75W-90 for "any temperature", or 80W-90 above 10c.

Rather than stating what vis I'm shooting for I indicated I wanted superior cold weather performance.

Thanks.

 

[Pablo]

A bit of a sticky wicket.

Given1: You can't get there with a conventional fluid (I suspect you know that). As you stated - main goal being good cold weather performance.

Given2: You need GL-4 EP/AW protection.

Given3: You need the correct FM's for the synchros in all 4.

I suggest a home blend.

I would use 75% Amsoil MTG 75W-90/25% Amsoil MTF as a starting point.

 

[Jax_RX8]

BG Syncroshift II. It is a 70W80 GL-4 oil that is known for great shifting and excellent protection.

The lighter weight of this oil will provide the superior cold weather performance you are seeking.

I use this in my Mazda RX-8 (that also calls for a 75W90) and it shifts very well and has totally eliminated this transmission notorious "whine" from the syncros.

If you wanted to go a little thicker, you could mix BG Ultraguard - a GL4/GL5 combo fluid with a 75W90 weight - I actually use this in my 8's rear diff - also with much reduced gear whine.

Redline MTL/MT90 blend is also a good option along with AMSOIL's 2 trans fluids - MTF (Synchromesh style 70W80 GL4 and MTG (75W90 GL4)

 

[Yuk]

Assuming I bought a case of each, would I only use the blend in the VW and use a straight fill of one of the fluids in the Nissan and Mazda?

What are the individual strengths/benefits of MTG and MTF in your 75/25 blend?

 

[Pablo]

Originally Posted By: Yuk
Assuming I bought a case of each, would I only use the blend in the VW and use a straight fill of one of the fluids in the Nissan and Mazda?

What are the individual strengths/benefits of MTG and MTF in your 75/25 blend?


Here is what Amsoil says (and I'm guessing which engines yours have):
1991 Nissan Sentra - MTG
1999 Volkswagen Passat - MTG
2007 Mazda 6 - MTG

So - using the MTG as a very protective baseline in a warm place, I'm just saying use the MTF to lower cold temp properties, yet still give good shifting throughout the range, without much if any sacrifice in wear. I run about a 60/40 MTG/MTF in my Volvo 850 with M56 and it's perfect.

 

[Yuk]

Great, thanks!

 

[momomeister]

How about Redline MT-90?

 

[unDummy]

Straight MTG or MT90 would be great for all those vehicles. Since you're located up north, thinning either with MTF or MTL, should help with cold weather shifting. 75%MTG/MT90 with the rest MTF/MTL should be a good starting point. Amsoil/Redline make excellent GL4 products.