# MT Owners - Anybody changed gear oil yet?



## Aeroscout977 (Nov 25, 2010)

Make sure you get amsoils direct replacement for GMs synchromesh. I switched to amsoil in my Honda for the MT and it was probably the best money I spent on drivability concerns.


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## tecollins1 (Nov 6, 2011)

Someone might need to explain the oil gears a lil more because this is my 1st MT car I've bought and I have noticed that my stick is notchy at times and sometimes it is real smooth. Is it the same as auto trans oil or something completely diff. Thanks


Sent from my Autoguide iPhone 4 app


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## sciphi (Aug 26, 2011)

tecollins1 said:


> Someone might need to explain the oil gears a lil more because this is my 1st MT car I've bought and I have noticed that my stick is notchy at times and sometimes it is real smooth. Is it the same as auto trans oil or something completely diff. Thanks
> 
> 
> Sent from my Autoguide iPhone 4 app


It's something entirely different. The 2012's have a synthetic 70w-80 GL-4 gear oil in the transmission, not Dexron-VI like the automatics have. Very different fluids for very different missions. 

Thinking it over some more, I just may go with Amsoil's Synchromesh fluid in the spring. It's slightly thinner at operating temperature than Redline's 70w-80, so that means less parasitic drag from the oil.


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## 70AARCUDA (Nov 14, 2010)

...when you switch to some "other" gear lubricant, don't be surprised if GM threatens to disavow further engine/*powertrain* warranty.


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## sciphi (Aug 26, 2011)

70AARCUDA said:


> ...when you switch to some "other" gear lubricant, don't be surprised if GM threatens to disavow further engine/*powertrain* warranty.


I know, it'll be much harder obtaining warranty service if something goes wrong inside the transmission. It depends on the issue at hand. For synchronizer wear, I could see it. If it's a recall or TSB about transmission issues, it would be harder to pin it on my choice of fluid, as long as the fluid is similar to OEM and was installed correctly.


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## Aeroscout977 (Nov 25, 2010)

One of the main problems with switching to heavier gear oil is the size of the lubrication ports in the tranny. Ones recommending gear oil have a larger diameter ports to allow for the heavier oil to do its job when cold. I've heard of people using 80W in transmissions meant for the lighter weight oil but only in the summer time. I wouldn't make a switch like that in the winter.


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## sciphi (Aug 26, 2011)

GM has a TSB out allowing the use of the 2011's 75w-85 gear oil in the 2012's transmission due to supply issues getting the dealers the 2012-spec fluid. It's supposed to be "slightly heavier" than the 2012 gear oil, which I'm guessing means the 2012 uses a 70w-80 instead of a 75w-85. There are 70w-80 fluids besides the GM fluid, which is sourced from Castrol. I'm not too thrilled with the Castrol fluid, so alternatives are being considered.


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## 1877 iris ave (Sep 23, 2011)

here is a link to amsoils manual trans oil
AMSOIL - Synthetic Manual Transmission and Transaxle Gear Lube 75W-90 (MTG)

if you check the viscosity at 40 and 100 degrees C you will see that it is slightly higher than the factory fluid


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## sciphi (Aug 26, 2011)

And this is the fluid I was thinking of using: AMSOIL - Synthetic Manual Synchromesh Transmission Fluid (MTF) 

The MTG is simply too thick when warmed up. The MTF is lighter, and is more a direct replacement for the OEM 70w-80 in my opinion.


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## eagleco (May 3, 2011)

sciphi said:


> GM has a TSB out allowing the use of the 2011's 75w-85 gear oil in the 2012's transmission due to supply issues getting the dealers the 2012-spec fluid. It's supposed to be "slightly heavier" than the 2012 gear oil, which I'm guessing means the 2012 uses a 70w-80 instead of a 75w-85. There are 70w-80 fluids besides the GM fluid, which is sourced from Castrol. I'm not too thrilled with the Castrol fluid, so alternatives are being considered.


Any word on why they changed fluids on the 2012's? And if I want to stick with OE fluid on my '11 Eco, should I go with the 2012 spec fluid or stay with the 2011 spec fluid. In other words did they change something about the transmission, or did they find that a different weight fluid works better in the MT regardless of year?


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## sciphi (Aug 26, 2011)

I don't know why they changed. I'm guessing that the lighter fluid meant some EPA/CAFE fuel mileage benefit. From what I've heard, it's the same transmission but a different, slightly lighter, fluid for the 2012's. 

Staying OEM, I'd stick with the 2011-spec fluid on a 2011, and 2012-spec on a 2012. 

IMO, either year should be happy with nothing thicker than a 75w-85 GL-4 gear oil. GM's TSB seems to imply that, FWIW.


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## eagleco (May 3, 2011)

Thanks for the info. I used Redline MT-90 (75w-90) in both my Miata and Mazda 3, but it sounds like that may be a little too thick for the Cruze. Not sure what I'll use in my Eco. It still shifts fine, and with only 8k miles on it, I am in no rush to change it.


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## FatKidsCruze (Sep 2, 2011)

sciphi said:


> And this is the fluid I was thinking of using: AMSOIL - Synthetic Manual Synchromesh Transmission Fluid (MTF)
> 
> The MTG is simply too thick when warmed up. The MTF is lighter, and is more a direct replacement for the OEM 70w-80 in my opinion.


I would use caution with this as its only 5w30. It also does not meet GL-4 standards at least its not on any of the tech specs listed. And finally it does not say that it is compatible with GM Part #19259104, which is the part no. for 2012 Cruzes.

Actually according to AMSOIL there are NO product recommendations for MT fluid on any Cruze/Sonic platforms


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## lostmymind (Dec 15, 2011)

FatKidsCruze said:


> I would use caution with this as its only 5w30. It also does not meet GL-4 standards at least its not on any of the tech specs listed. And finally it does not say that it is compatible with GM Part #19259104, which is the part no. for 2012 Cruzes.
> 
> Actually according to AMSOIL there are NO product recommendations for MT fluid on any Cruze/Sonic platforms


You can use different weights you just have to know what you are switching it with and what effects it will have on different parts. Chances are your warranty goes bye bye if you do this though. Mitsu is a perfect example of this. Unless you use the $90 Mistubishi fluid, you can say bye to your warranty when you have to take it in for issues


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## sciphi (Aug 26, 2011)

FatKidsCruze said:


> I would use caution with this as its only 5w30. It also does not meet GL-4 standards at least its not on any of the tech specs listed. And finally it does not say that it is compatible with GM Part #19259104, which is the part no. for 2012 Cruzes.
> 
> Actually according to AMSOIL there are NO product recommendations for MT fluid on any Cruze/Sonic platforms


Motor oil and gear oil are on two different weighting systems. So a 70w-80 gear oil is roughly equivalent to a 5w-30 motor oil. Look up some specs for a 5w-30 motor oil. The Synchromesh and Redline MTL are very close in viscosity to a 5w-30 motor oil. Some Honda owner's manuals even used to say that 5w-30 motor oil was okay as a temporary replacement for gear oil since it met warm viscosity specs for a 75w-85 gear oil, and had enough additives to get by for a few hundred miles until a real gear oil could be located. 

While Amsoil Synchromesh doesn't list GL-4 specification, it does say good for brass synchros. I know some GL-5 fluids are also compatible with brass. It also doesn't say it's not compatible. So it's a tossup. 

That leaves us with the Redline MTL. That does specify GL-4, and is a 70w-80 gear oil. It's got the specs, it's got the viscosity, I may give it a shot.


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## FatKidsCruze (Sep 2, 2011)

Hmmm I never thought about that. But now that you mention it I used AMSOIL synchromesh in my teg, but I had to use a smidgin of my 5w30 motor oil.

I guess I was thinking about keeping the factory warranty for as long as I can.


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## sciphi (Aug 26, 2011)

I'm NOT thrilled with shift quality, and a big part of that is the fluid. IMO, Redline makes generally better products than Castrol. Unfortunately, GM has a supplier contract with Castrol for the factory fill. And the FF isn't too great, again IMO. 

I'd also much rather use a superior aftermarket product to prevent a warranty claim in the first place instead of staying OEM and needing a warranty claim. And, with how much driving I'm doing, the car will be out of warranty on miles instead of time. 

This is seeming reminiscent of the wars over which ATF to use in a Honda transmission! Some folks say stick to the thankfully phased out Z1, while others sing the praises of aftermarket full-synthetic ATF's, including Amsoil and Redline. And both camps have valid points worth considering, and lots of experiences to back up their points of view.


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## FatKidsCruze (Sep 2, 2011)

I agree with the shift quality with the factory fill, its hit or miss sometimes. I switched over to AMSOIL signature 5w30 in the engine already.


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## sciphi (Aug 26, 2011)

FatKidsCruze said:


> I agree with the shift quality with the factory fill, its hit or miss sometimes. I switched over to AMSOIL signature 5w30 in the engine already.


I know. Sometimes it shifts great, then other times it shifts like dog doo. If it was consistent one way or the other, I would write it off as a quirk of the transmission. Seeing how it changes, that leads me to think it's a fluid issue.


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## FatKidsCruze (Sep 2, 2011)

Are you waiting til spring to change it or will you be doing it sooner. I would like to know how the AMSOIL synchro fluid fairs in the M32 trans. I have absolutely no complaints in my Integra with it.


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## sciphi (Aug 26, 2011)

Waiting until spring. The weather's too unpredictable now for outside car work. I don't have a garage, so getting the car level-ish with the front wheels on ramps while the rears are on jackstands would be much less fun in the winter cold. 

I'd get the Redline MTL 70w-80, as it's the most direct replacement for the OEM fluid I've found so far.


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## FatKidsCruze (Sep 2, 2011)

Amen brother, I'm an outside car guy too lol. I have been neglecting my Cruze's exterior because of the cold, well and the fact that it's dark when I get home from work.


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## sciphi (Aug 26, 2011)

I did more reading on the Redline MTL, and about nobody has bad things to say about it for a lightweight GL-4 gear oil. Even the Mustang guys with their MT82 transmissions that blow up when they sneeze are loving it. Seeing so much good said about the fluid, it's going into my transmission in the spring.


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## sciphi (Aug 26, 2011)

Update: With 19k miles on the car, I bit the bullet and ordered some Amsoil MTF (Synchromesh). It's roughly 70w-80, and is GL-4 compatible. I chose it over Redline 70w-80 due to hearing that the MTF was more consistent long-term than the Redline. I'll see how the car reacts to the MTF. The weather is finally warm enough to do car work outside!

Searching the European English-language forums for cars that use the M32 transmission, they're using 75w-80 and 70w-80 oils, so I believe (note the believe!) I'm okay using a 70w-80 fluid in my M32 transmission.

Here's a link showing the fill and level plugs on an Opel Astra VXR: http://www.z22se.co.uk/forum/threads/m32-gearbox-oil-change.19538/

The drain plug is somewhere on the differential.


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## Campuscop2003 (Mar 5, 2011)

Sorry if this was answered already, how many quarts does the transmission take? Thinking about changing the fluid before I go on vacation this year. Also the drain plugs dont need replaced do they? Thought I read somewhere that they did. Thanks


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## XtremeRevolution (Jan 19, 2012)

Campuscop2003 said:


> Sorry if this was answered already, how many quarts does the transmission take? Thinking about changing the fluid before I go on vacation this year. Also the drain plugs dont need replaced do they? Thought I read somewhere that they did. Thanks


IIRC, the MT takes 2 quarts, the AT takes 8. Your actual drain and re-fill amounts may vary.


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## Chevy Customer Care (Oct 29, 2011)

Campuscop2003 said:


> Sorry if this was answered already, how many quarts does the transmission take? Thinking about changing the fluid before I go on vacation this year. Also the drain plugs dont need replaced do they? Thought I read somewhere that they did. Thanks



Campuscop2003,
I would like to assist you with this question. Can you please send me a PM with your VIN? I look forward to hearing back from you. 
Thank you,
Stacy Chevrolet Customer Service


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## Campuscop2003 (Mar 5, 2011)

Did some online research and found my answer. Thanks so much anyways for offering to help!!! And thanks again for helping me with the other issue this week. You've been awesome!



Chevy Customer Service said:


> Campuscop2003,
> I would like to assist you with this question. Can you please send me a PM with your VIN? I look forward to hearing back from you.
> Thank you,
> Stacy Chevrolet Customer Service


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## Chevy Customer Care (Oct 29, 2011)

Campuscop2003 said:


> Did some online research and found my answer. Thanks so much anyways for offering to help!!! And thanks again for helping me with the other issue this week. You've been awesome!



Campuscop2003,
I am happy to hear that you found your answer! I am always here to help so please don't hesitate to contact me with any questions, comments or concerns that you may have! 
~Stacy Chevrolet Customer Service


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## sciphi (Aug 26, 2011)

FatKidsCruze said:


> Are you waiting til spring to change it or will you be doing it sooner. I would like to know how the AMSOIL synchro fluid fairs in the M32 trans. I have absolutely no complaints in my Integra with it.


A few months later, I have an answer for you. The Amsoil Synchromesh seems to do just fine in a Cruze transmission. I swapped it out yesterday, and put about 70 miles on it. The shifting is definitely smoother. The funky 1-2 shift is gone. No complaints about the 2-3 shift, either. I can't remember the last time this transmission shifted this well. It's a noticeable improvement over the factory fill, at least in this spring weather. I'll report back after putting a few thousand miles on this fluid to see how it handles high heat.


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## bryanakron40 (Nov 8, 2012)

To bring this back from the dead. I do not know of any GL-5 fluids that are ok to use in a modern brass synchro manual transmission. I saw where someone said some GL-5 fluids are compatible. The friction modifiers in the GL-5 are the issue, not the base fluid. I went there with a Hyundai dealer I worked at. The parts guys figured GL-5 must be better than GL-4 and we rebuilt many a trans that year.


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## Greasemonkey2012 (Jul 8, 2012)

sciphi said:


> Update: With 19k miles on the car, I bit the bullet and ordered some Amsoil MTF (Synchromesh). It's roughly 70w-80, and is GL-4 compatible. I chose it over Redline 70w-80 due to hearing that the MTF was more consistent long-term than the Redline. I'll see how the car reacts to the MTF. The weather is finally warm enough to do car work outside!
> 
> Searching the European English-language forums for cars that use the M32 transmission, they're using 75w-80 and 70w-80 oils, so I believe (note the believe!) I'm okay using a 70w-80 fluid in my M32 transmission.
> 
> ...



u know the 70w80 fuchs oil is a GL5


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