# M. Trans lube for economy



## DrVette (Dec 6, 2011)

Anyone know the model # for the ECO trans (2012) M32 ?

Does it call for GL-4

Amsoil MTG 75/90 is this a shifting improvement?
How about viscosity & drag compared to stock lube.

Any warranty issues?

Other "Econo" substitutes?

Thanks

AMSOIL Manual Transmission & Transaxle Gear Lube 75W-90


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## Greasemonkey2012 (Jul 8, 2012)

I have the amsoil 75w90 it's good Trans oil when cold a little hard to shift but when it warms up its perfect 


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## Hoon (Mar 18, 2012)

You already have the Eco stuff in there from the factory. It's junk, too thin to work effectively after the first 15K miles or so. 

75W-90 GL4 is best IMO. 

I'm running 80W90 and it's too thick when cold.


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## OnlyTaurus (Mar 20, 2012)

+1 for 75W-90 GL4. That's what I put in after in stalling the new clutch.


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## sciphi (Aug 26, 2011)

Amsoil Synchromesh is pretty much a 70w-80 gear oil. I've had it in my transmission for 31k miles now, and have only good things to say about it. Cold and warm shifting are great, and the shifting is consistent and predictable. It also eliminated my 2nd gear grind. I wanted a better lube that was still fuel-efficient, and found it. My fuel economy stayed the same after swapping it out. 

If you're not beating on the car that much, Synchromesh is the way to go. If you're flogging the daylights out of a tuned car all the time, get 75w-90. 

Don't get a GL5 gear oil. GL5 gear oils have too much friction modifier and extreme-pressure additive for the synchros. A dual-rated GL4/GL5 oil has been shown to work.


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## DrVette (Dec 6, 2011)

OnlyTaurus said:


> +1 for 75W-90 GL4. That's what I put in after in stalling the new clutch.


What to do, Amsoil's product guide doesn't show the Cruze.
Can I assume their product doesn't please GM or they did not buy the "rights" to put the GM approved stamp, like Dexos1 ?

AMSOIL Online Product Application Guide


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## DrVette (Dec 6, 2011)

sciphi said:


> Amsoil Synchromesh is pretty much a 70w-80 gear oil.
> 
> If you're not beating on the car that much, Synchromesh is the way to go. If you're flogging the daylights out of a tuned car all the time


That's me, I have some clear roads where I can get 120~ with no traffic, otherwise I'm in hypermile mode.


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## DrVette (Dec 6, 2011)

Synchromesh AMSOIL Manual Synchromesh Transmission Fluid 5W-30is rated as 5w/30, no matter to me.
But it is not a GL-4, AFAIK per the data .pdf.

Amsoil MTG is a GL-4 lube, but the 75/90 weight seems heavy for the Cruze's "sewing-machine" Tranny.
Well, in cold weather & for mpg.
Experiences ?

AMSOIL Manual Transmission & Transaxle Gear Lube 75W-90


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## sciphi (Aug 26, 2011)

Gear oil and motor oil use two different viscosity scales. A 5w-30 motor oil is very roughly equivalent to a 75w-85 or 70w-80 gear oil. Amsoil put 5w-30 on there since some older manual transmissions specified 5w-30 motor oil, back in the API SF and SJ days when motor oils had different anti-wear additives in them. Synchromesh is compatible with yellow metals, which is a hallmark of GL4-compatible gear oils. 

While Amsoil's Synchromesh isn't GM-certified, it does work very well in our transmissions. I've had the stuff in for 30k miles now, and the transmission still shifts beautifully. I'll drain it in another 20k miles and do a UOA on it to see how it is doing.


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