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Discussion Starter #1 (Edited)
Starting this off in the Gearhead section so we can talk about it before we open it up.

Referring to our manual transmissions, it seems that the biggest problem is heat. I didn't know this until I kept an eye on the Trifecta boards, where discussions to the Sonic forums were posted.

http://www.sonicownersforum.com/forum/transmission-discussion/6217-building-stronger-6-spd-man-trans.html

They have a guy there who was intelligent enough to keep an eye on the Vauxhall boards, where they discovered that heat is the issue.

from the AstraVXRforums
With the M32 heat is its worst enemy, it’s a 3 shaft design all squeezed into a compact casing.The box build’s up heat and the oil gets cooked and loses its lubrication qualities, to make matters worse there is no service interval on the gear oil so bearing's wear and synco’s go. One of the best preventative measures is to change the oil using a fully synthetic gear lube, and if you use the car very hard, have a lot of power or use one on track then change the oil regularly. I know of a couple of people in competition who have used a gearbox oil cooler and this has all but eliminated failures for them (Bo being one of them). I’ve been asked to put together an oil cooler kit for this and will be doing this in the next month for people who use them hard. Unfortunately we are not allowed them in the Production touring car Championship, so we run a breather catch tank and ½ a litre of more oil to spread the thermal load which helps and we also change the oil every round!

So if you have a M32 get the oil changed, we use a 75-90 synthetic gear lube, hope this helps.
If you take a long read through the vauxhall forums, the m32 failures are happening to all too often to daily drivers that don't race at all.

The issue of heat stems from the compact 3 shaft design. I will probably run my stock MZ4 til it fails, but when it does, I'll have a replacement ready and hopefully fitted with a cooler.
I got pretty intimate with the M32 this week after doing 2 R&R's

It's a pretty straightforward job and can be done in approx 3-4 hrs once you're familiar with it all.

I did notice that my Redline Synth gear oil was pretty smoked after just 8k mi.
And also there was evidence of break-in metal sparkles in the spent oil.

So from here on out I'm going to change the gear oil every 5k........ if my M32 is still alive in 5k.
 

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Discussion Starter #2 (Edited)
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.
 

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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.
 

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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.
 

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Discussion Starter #5
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.
 

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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.
 

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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.
 

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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.
 

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Discussion Starter #9
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.
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.
 

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...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.
 

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Discussion Starter #11
...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.
 

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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.
 

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Discussion Starter #13 (Edited)
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.
 

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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.
 

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Discussion Starter #15
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.
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.
 

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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.
 

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Discussion Starter #17
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.
 

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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.
 

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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.

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?
 

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Discussion Starter #20
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.
 
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