# M32 Transmission Heat & Reliability



## XtremeRevolution (Jan 19, 2012)

Moving forward, there are a few things that caught my eye. 

1. how long does our replacement synthetic transmission fluid last? 
2. should we be telling people that this is absolutely necessary for the longevity of their transmission due to the heat resistance of the synthetic fluid over the crap the Cruze came with?
3. we need to be keeping an eye on ways to cool this transmission down if we want it to last hundreds of thousands of miles under spirited driving.

We should at some point open this discussion up to the public.


----------



## sciphi (Aug 26, 2011)

1. Amsoil recommends changing the Synchromesh at 50k miles if no other recommendation is given. That's a fair change interval, and is likely about right for the M32. At 35k miles on the Synchromesh, it's not as crisp as it was when fresh. It's about 85% of what it was when brand-new. I'm counting the miles until I change it. Look for a UOA on it, too. UOA is cheaper than a new transmission...
2. The Cruze likely does come with a synthetic fluid. Castrol BOT 402 is supposed to be synthetic. Then again, it's BP/Castrol so it's crap by definition. Changing to a better synthetic, like Amsoil, will help. Changing the fluid regularly with a quality synthetic is best practice. 
3. Using a better synthetic oil and changing it regularly will likely be the best prescription for transmission life. Changing the OEM stuff out early in the car's life, say by 15k miles, then every 40-50k miles after that with Amsoil Synchromesh (which I do feel is the best fluid for the application for most folks based on RP's synchromesh being pretty thin and Redline degrading fairly rapidly) should give the transmission a long life. 

The biggest thing is getting folks to realize that "lifetime filled" means 5 years or 100k miles of the powertrain warranty, and that if they plan on keeping the car longer than the powertrain warranty, they'd better do some maintenance on the transmission.


----------



## Hoon (Mar 18, 2012)

That explains why the stock fluid turns to piss in < 1 year. I figure with the heavy weight conventional fluid i have in there it will start to break down and thin out, and be good for 20-30K.


----------



## XtremeRevolution (Jan 19, 2012)

Hoon said:


> That explains why the stock fluid turns to piss in < 1 year. I figure with the heavy weight conventional fluid i have in there it will start to break down and thin out, and be good for 20-30K.


Sure does. I know what Dave said as far as manufacturer recommended intervals, but I don't think this is a typical transmission. A 20-30k full syn fluid change (every 3 oil changes?) might be necessary.


----------



## Hoon (Mar 18, 2012)

XtremeRevolution said:


> Sure does. I know what Dave said as far as manufacturer recommended intervals, but I don't think this is a typical transmission. A 20-30k full syn fluid change (every 3 oil changes?) might be necessary.


Very possible. I'll definitely go 75W90 GL4 synthetic next time, just didn't have any available for this change and didn't want to wait for it. It'll be interesting to see how the conventional stands up. I wish i had a way to monitor trans temp, but for my use of the car it isn't worth the time to install a gauge.


----------



## Hoon (Mar 18, 2012)

Another thing is engine oil temps. On a 30* night:

I left a bar in boston (sober) at around 1AM, set my cruze control at 85, turned up the music and just relaxed. I had Torque running just to see what things would look like. I got to Newport RI (home) an hour later. Oil temps sat at 255* the whole time. These aren't exactly extreme conditions, and 255 is pretty hot. I wonder what i get towing in the summer...:brave:

I definitely would not recommend anything besides full synthetic, and even then with hard driving the long service life in hot conditions requires a good synthetic.


----------



## 70AARCUDA (Nov 14, 2010)

Two things to remember about "european" driving conditions (as applied to GM-Opel transmissions):

1) yes, it gets hot in southern europe, but NOT as hot as in USA southwest deserts.

and

2) europe is more about short, twisty, congested city and mountainous drives than USA's LONG distances, at high speeds, for _long_ periods of time.

...driving conditions, which when combined, tend to "cook" both automatic and manual transmissions.


----------



## XtremeRevolution (Jan 19, 2012)

70AARCUDA said:


> Two things to remember about "european" driving conditions (as applied to GM-Opel transmissions):
> 
> 1) yes, it gets hot in southern europe, but NOT as hot as in USA southwest deserts.
> 
> ...


While I certainly agree with you, I am under the impression that this is a special breed of transmissions that presents a set of problems not previously experienced. Reduced fluid capacity means it will all heat up more quickly, and the tight spaces means heat has fewer places to go. The high operating temperature of the engine compared to other cars of the past probably doesn't help that cause. 

I would be interested in the development of a large bolt-on transmission heatsink if it may help this cause, but I haven't looked at it closely enough to know if it's even possible. Plumbing an oil cooler with a pump would be an expensive endeavor (think $500 minimum). 

I believe this is something we need to address very soon and make known to our community so they can at least take the first step in swapping out a better synthetic fluid as preventative maintenance. 

That COMG project is starting to look more and more important as each week goes by.


----------



## 70AARCUDA (Nov 14, 2010)

...let me clarify: those are transmissions _designed_ in europe for european _driving_ conditions that GM has "...brought over..." and stuck into North American vehicles and driving conditions for which they were NOT originally designed. They were NOT designed for our driving conditions...almost "square-peg shoved into "round-hole" situation.


----------



## XtremeRevolution (Jan 19, 2012)

70AARCUDA said:


> ...let me clarify: those are transmissions _designed_ in europe for european _driving_ conditions that GM has "...brought over..." and stuck into North American vehicles and driving conditions for which they were NOT originally designed. They were NOT designed for our driving conditions...almost "square-peg shoved into round-hole" situation.


Aaaaah! I see where you went with that. I thought you were saying that the conditions were easier on the transmission in Europe, but it actually seems they are harder on the transmissions here in the US.


----------



## titan2782 (Nov 4, 2011)

XtremeRevolution said:


> I would be interested in the development of a large bolt-on transmission heatsink if it may help this cause


Best bet would be a finned pan. These are very common in the performance automatic world. My issue with a bolt on heat sink is the thermal transfer ability of cast iron (I'm assuming our pans are cast, what are they?).

Automatics certainly have an advantage because they already have a heat exchanger that can be easily swapped for a bigger one.

Definitely time to change my fluid. I think napa carries amsoil synchromesh. I know they carry amsoil products.


----------



## XtremeRevolution (Jan 19, 2012)

titan2782 said:


> Best bet would be a finned pan. These are very common in the performance automatic world. My issue with a bolt on heat sink is the thermal transfer ability of cast iron (I'm assuming our pans are cast, what are they?).
> 
> Automatics certainly have an advantage because they already have a heat exchanger that can be easily swapped for a bigger one.
> 
> Definitely time to change my fluid. I think napa carries amsoil synchromesh. I know they carry amsoil products.


A finned pan would be great if it wouldn't be too difficult to be replaced. It was really just a random thought on the lines of a finned pan but something that may not require a pan drop. I believe our transmission is die cast aluminum, so a heatsink might be effective if it could be attached well. I don't think it's done before, and I'm sure there's a reason for it. Having a finned pan developed might prove to be a bit of a challenge though. 

In any case, I wanted to discuss this with you guys first before we open it up to everyone else. I'm thinking that we should recommend a fluid change as a bare minimum, and start looking for ways to keep these transmissions cooler.


----------



## titan2782 (Nov 4, 2011)

XtremeRevolution said:


> A finned pan would be great if it wouldn't be too difficult to be replaced. It was really just a random thought on the lines of a finned pan. I believe our transmission is die cast aluminum, so a heatsink might be effective if it could be attached well.


Pan thickness will be an issue as well. I imagine our pans are thick.

BUT, either way I have to take the XR approach on this one. 1) What is the optimal operating temperature for the fluid being used 2) What is the absolute temperature of the oil?

Sure, it may get hot but oils are designed for their intended purpose. Scan gun on the pan won't do much good because you're going to get heat soak from the engine and ambient heat. It may be that the pan is shielding the oil. 

Does anyone have any solid temp readings of the actual fluid?

I'd be more concerned with the aftermarket fluids eating away at the metals as others have suggested, more so than overheating.


----------



## XtremeRevolution (Jan 19, 2012)

titan2782 said:


> Pan thickness will be an issue as well. I imagine our pans are thick.
> 
> BUT, either way I have to take the XR approach on this one. 1) What is the optimal operating temperature for the fluid being used 2) What is the absolute temperature of the oil?
> 
> ...


I don't know what the operating temperature is, but my understanding is that the force is high enough on the moving parts and bearings that the oil heats up to the point of failure. This is what I've been getting from reading that sonic owner's thread. Those who were able to keep their transmissions cooler were able to put more power through them without failure. 

I'd have to go back through the thread and find the exact parts referencing it, but there was something about there being 3 shafts inside a very small space and it causing extra stress, thus creating extra heat. It would be nice to be able to tell how hot the fluid gets, but short of a drain plug that had a sensor on the inner end of it and a wire sticking out, I don't know how you'd do it. 

There isn't really a concern with aftermarket fluids eating away the metals as long as you use the right oil. If someone goes out and grabs a random fluid without doing any research, then they'll probably have some problems, but as long they stick to what we know is approved for the metals used in our transmission, they'll be fine. I think our two options right now are Royal Purple (I forget which exact model), and Amsoil Synchromesh. I use the latter and it has been excellent.


----------



## titan2782 (Nov 4, 2011)

XtremeRevolution said:


> I don't know what the operating temperature is, but my understanding is that the force is high enough on the moving parts and bearings that the oil heats up to the point of failure. This is what I've been getting from reading that sonic owner's thread. Those who were able to keep their transmissions cooler were able to put more power through them without failure.
> 
> I'd have to go back through the thread and find the exact parts referencing it, but there was something about there being 3 shafts inside a very small space and it causing extra stress, thus creating extra heat. It would be nice to be able to tell how hot the fluid gets, but short of a drain plug that had a sensor on the inner end of it and a wire sticking out, I don't know how you'd do it.
> 
> There isn't really a concern with aftermarket fluids eating away the metals as long as you use the right oil. If someone goes out and grabs a random fluid without doing any research, then they'll probably have some problems, but as long they stick to what we know is approved for the metals used in our transmission, they'll be fine. I think our two options right now are Royal Purple (I forget which exact model), and Amsoil Synchromesh. I use the latter and it has been excellent.


Aftermarket ATF temp gauges are usually drain plug replacements. I had one on my Camaro. Back in the day, the ATs didn't have a place to take temps and some didn't even have drain plugs. Problem is finding one to match our plug.


----------



## XtremeRevolution (Jan 19, 2012)

titan2782 said:


> Aftermarket ATF temp gauges are usually drain plug replacements. I had one on my Camaro. Back in the day, the ATs didn't have a place to take temps and some didn't even have drain plugs. Problem is finding one to match our plug.


Any idea what the thread on our plug is? 

I wouldn't mind hooking up a simple, digital gauge to monitor the transmission fluid temp. I didn't realize it would be quite that easy.


----------



## 70AARCUDA (Nov 14, 2010)

XtremeRevolution said:


> Any idea what the thread on our plug is?
> 
> I wouldn't mind hooking up a simple, digital gauge to monitor the transmission fluid temp. I didn't realize it would be quite that easy.


...depending upon how "good" you are with Vince, try asking him if there's a way to display the oil transmission temperature through his "tune" program...at least for the automatic transmissions (not sure about the manuals) because I vaguelly recall reading that the TCM monitors the fluid temperature partly as a self-preservation function (TCM is literally inside the AT housing, immersed in ATF fluid). So, if the TCM gathers the temperature, there's a VERY good possibility it shares that info with the ECM, which *should* enable it to be "pulled" from the OBDII connector.


----------



## OnlyTaurus (Mar 20, 2012)

Hoon said:


> Very possible. I'll definitely go 75W90 GL4 synthetic next time, just didn't have any available for this change and didn't want to wait for it. It'll be interesting to see how the conventional stands up. I wish i had a way to monitor trans temp, but for my use of the car it isn't worth the time to install a gauge.


I'm especially glad I decided to use the Royal Purple MaxGear 75w90 GL-4 after finding this out. I would suggest this fluid to try.

Max Gear is recommended for use in truck and automotive front or rear differentials, manual transmissions and lower gear units of marine engines that specify use of an API GL-5 or GL-4 fluid. It is non-corrosive to soft yellow metals (brass, bronze, copper, etc.) and synchronizer safe

Max Gear is an ultra-tough, high performance automotive gear oil designed to provide maximum protection to heavily loaded gears while maximizing power throughout the drive train. Max Gear outperforms ordinary gear oils by combining the highest quality synthetic oils with Royal Purple’s proprietary Synerlec additive technology. Max Gear makes gears run smoother, quieter, cooler and longer without overhauls. Max Gear is formulated with a friction modifier additive – no additional additives are necessary.



XtremeRevolution said:


> Any idea what the thread on our plug is?
> 
> I wouldn't mind hooking up a simple, digital gauge to monitor the transmission fluid temp. I didn't realize it would be quite that easy.


Did you get my bolt numbers and find a plug to use?


----------



## XtremeRevolution (Jan 19, 2012)

Ryan, I got your bolt numbers. This will be a long-term thing for me as I have a lot of other projects going on, unless someone else does it before me. 

I think I'm going to open this up to the rest of the forum for further discussion. 

Biggest thing right now is that if you haven't changed your factory transmission fluid out yet, DO IT.


----------



## BowtieGuy (Jan 4, 2013)

XtremeRevolution said:


> Building a Stronger 6-spd Man Trans - Page 13 - Chevy Sonic Owners Forum


Link doesn't work.

I have been following those changing out the transmission fluid in their manuals for awhile now but was really hesitant as it seemed there wasn't a general consensus on what fluid would actually be considered up to spec for use with our M32 transmissions. But with so many others on the Sonic/other M32 trans owner forums noticing this, even with only DD use, its hard to argue that the Castrol fluid itself is even up to the spec in the first place. The only real problem convincing people is, do we change out the Castrol junk now and risk voiding our powertrain warranties for any possible problems down the road? Or stick with the Castrol fluid until it demolishes our transmissions while it's still under warranty?

EDIT: Is the newer 2012+ GM part number fluid still Castrol? I thought the new stuff was a lighter viscosity than the 2011 part number?


----------



## XtremeRevolution (Jan 19, 2012)

Link changed for some reason. Here it is:

http://www.sonicownersforum.com/for...n/6217-building-stronger-6-spd-man-trans.html

I don't know about the new 2012 GM fluid or whether it's any different than the 2011 fluid. 

I would change it now. You could keep it later, and have the transmission fail at 110lk or 120k miles and foot the bill of the rebuild. Since we do know of at least two easily obtainable fluids that serve as excellent replacements and are safe for use with the metals found in our transmission, I refer you to my previous recommendation. Change out the OEM fluid ASAP for something of higher quality that has a higher heat tolerance.


----------



## Greasemonkey2012 (Jul 8, 2012)

I'm Gona run fuchs Titan sintofluid 75w80 


Sent from AutoGuide.com App


----------



## XtremeRevolution (Jan 19, 2012)

Greasemonkey2012 said:


> I'm Gona run fuchs Titan sintofluid 75w80
> 
> 
> Sent from AutoGuide.com App


Looking forward to a review. 

I'm not at all saying it's bad, but for anyone looking to change their fluid, we have successfully tested the Royal Purple fluid that Ryan (OnlyTaurus) used - noted on page 2 - and Amsoil Synchromesh. I would feel safe recommending either of those as a replacement, but certainly wouldn't mind having another option. 

To confirm, is Titan Sintofluid safe with the metals used in our transmission? Also, isn't that a tad bit higher viscocity than 75w90? I talked to Hoon, and he noted that the shifting was a bit erratic if you use too thick of a fluid.


----------



## EcoDave (Mar 7, 2013)

BowtieGuy said:


> The only real problem convincing people is, do we change out the Castrol junk now and risk voiding our powertrain warranties for any possible problems down the road? Or stick with the Castrol fluid until it demolishes our transmissions while it's still under warranty?



Wait... How the heck does changing our factory transmission fluid void our warranty???


----------



## blk88verde (Apr 30, 2011)

> I'm especially glad I decided to use the Royal Purple MaxGear 75w90 GL-4 after finding this out. I would suggest this fluid to try.


Ordered RP MaxGear 75w90 this evening, picking up tomorrow. I have to say my 2011 ECO MT seems to perform flawlessly at 15.4k miles on it - so far with the factory fill.


----------



## Greasemonkey2012 (Jul 8, 2012)

XtremeRevolution said:


> Looking forward to a review.
> 
> I'm not at all saying it's bad, but for anyone looking to change their fluid, we have successfully tested the Royal Purple fluid that Ryan (OnlyTaurus) used - noted on page 2 - and Amsoil Synchromesh. I would feel safe recommending either of those as a replacement, but certainly wouldn't mind having another option.
> 
> ...




well in Europe all the guy on the VXR forms their running that fluid and they say its amazing stuff well all the Fuchs product is good stuff 

Thats from the Opie oil man 

If you use really basic oils then using GL5 instead of GL4 can cause problems, but GL5 oils from reputable companies use the same additive pack as in a GL4, just in larger quantities, so is fine to use in a GL4 application. The Sintofluid 75w-80 is a really good option. I know a couple of people were having real problems with vauxhall gearboxes and the Sintofluid sorted them out. One guy had a vivaro and the gearbox had been replaced twice by the time it hit 60k. When he had the box fitted at 60k, he put in the Sintofluid and it's been fine. He must be on about 120k by now.

http://www.opieoils.co.uk/p-981-fuchs-titan-sintofluid-sae-75w-80-synthetic-manual-transmission-fluid.aspx


----------



## XtremeRevolution (Jan 19, 2012)

blk88verde said:


> Ordered RP MaxGear 75w90 this evening, picking up tomorrow. I have to say my 2011 ECO MT seems to perform flawlessly at 15.4k miles on it - so far with the factory fill.


If you think it has been performing flawlessly with factory fill, I can't wait to hear what you have to say when you replace the fluid!



Greasemonkey2012 said:


> well in Europe all the guy on the VXR forms their running that fluid and they say its amazing stuff well all the Fuchs product is good stuff
> 
> Thats from the Opie oil man
> 
> ...


Good info to know. Where are you buying it? I haven't heard of it before here in the US. I did find it on amazon.com, but it's $33 per liter!

Volvo (76-95) Manual Transmission Fluid (1 Liter) FUCHS 75W-80 oil : Amazon.com : Automotive


----------



## Greasemonkey2012 (Jul 8, 2012)

They sell it local store where I live 10$ a litre 


Sent from AutoGuide.com App


----------



## sciphi (Aug 26, 2011)

A word of warning: Whatever synthetic oils are used, make sure they are GL4 and/or yellow metal (brass/bronze) compatible! There are still some old-school GL5 fluids out there that will wreck a transmission calling for GL4 fluid. 

Agreed with XR, if you are not having issues with the stock fluid, wait until it's changed out to appreciate the difference. 


Sent from AutoGuide.com Free App


----------



## 70AARCUDA (Nov 14, 2010)

...apparently even GM is aware of metal particles in engines & transmissions:

The Job of Magnetic Drain Plugs


----------



## sciphi (Aug 26, 2011)

For more reading on MT lubes, MolaKule on Bobistheoilguy.com posted this thread over there in 2009. I feel the first post is applicable to this discussion.

Link to Bobistheoilguy: Synchromesh Manual Transmission Lubricants - Bob Is The Oil Guy


----------



## Greasemonkey2012 (Jul 8, 2012)

Well guys I got the Fuchs Titan Sintofluid 75w80 and the shifting is so beautiful and it's only been a day


----------



## Greasemonkey2012 (Jul 8, 2012)

Heres what used , u can get it this at any VW dealership or any German car dealership or online


----------



## SportBilly (Nov 25, 2013)

anyone have done the tans cooler??


----------



## XtremeRevolution (Jan 19, 2012)

SportBilly said:


> anyone have done the tans cooler??


Not an option unless you want to run an inline pump as well. 

Sent from AutoGuide.com App


----------

