# Diesel Transmission external cooler



## diesel (Jun 8, 2013)

Just for the record, I am at 151K miles on the original unmodified transmission without issue. I did change to Amsoil fluid at some point after 100K (don't remember the exact miles, but at least 30K miles ago)


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## LiveTrash (May 24, 2015)

diesel said:


> Just for the record, I am at 151K miles on the original unmodified transmission without issue. I did change to Amsoil fluid at some point after 100K (don't remember the exact miles, but at least 30K miles ago)


Looks like Amsoil is the way to go then. I've been looking around at my options and it seems Amsoil is going to be the one I'll go for.


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## boraz (Aug 29, 2013)

LiveTrash said:


> Looks like Amsoil is the way to go then. I've been looking around at my options and it seems Amsoil is going to be the one I'll go for.


100k on brand x, 51k on brand y.....brand y is better how?


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## boraz (Aug 29, 2013)

outdoorjr said:


> I do not believe that it should be normal temp at 210-220. It should be at least 175-195.


what temp do you believe that the torque converter will lock up at?


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## outdoorjr (Jan 17, 2016)

boraz said:


> what temp do you believe that the torque converter will lock up at?


Normally, TC lock up at top gear (sixth gear) It should be under 200. Tomorrow, I will be driving and if it hits 220 again, I will try and change from D to M5 to see if TC will lock out and get temp down. Very curious about it.


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## outdoorjr (Jan 17, 2016)

diesel said:


> Just for the record, I am at 151K miles on the original unmodified transmission without issue. I did change to Amsoil fluid at some point after 100K (don't remember the exact miles, but at least 30K miles ago)


I was looking at 2014 Cruze Owner Manual - Maintenance Schedule shows "change automatic transmission fluid, change filter if serviceable at 45K. On any Chevy transmission, I normally get the fluid change at every 30K. I am considering to get Amsoil fluid after reading many positives.


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## boraz (Aug 29, 2013)

outdoorjr said:


> Normally, TC lock up at top gear (sixth gear) It should be under 200. Tomorrow, I will be driving and if it hits 220 again, I will try and change from D to M5 to see if TC will lock out and get temp down. Very curious about it.


the trans is designed to lock up in any gear above 1st if temps get high, higher than youre worried aboot

and basing a fwd transmission's temps with a rwd transmission's temps has zero basis.

everything is fine.


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## Aussie (Sep 16, 2012)

The oil usually runs hotter than the radiator fluid or you wouldn't get any cooling at all. 220 sounds good to me especially with that mileage.


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## pandrad61 (Jul 8, 2015)

> Hi - Did anyone have installed transmission external cooler yet? I am considering to install transmission external cooler on my diesel cruze .


you do realize that the cruze diesel already has a external oil to air tranny cooler that is actually very big


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## pandrad61 (Jul 8, 2015)




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## pacolino (Aug 1, 2015)

There you go...good point!

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## pandrad61 (Jul 8, 2015)

Aussie said:


> The oil usually runs hotter than the radiator fluid or you wouldn't get any cooling at all. 220 sounds good to me especially with that mileage.


this is the reason i bypassed the in radiator oil to water cooler on my grand cherokee. its another point of failure to get coolant in a slush box and BOOOOMMM!!!!. as you stated its actually more of a heater lol. once my warrenty is out i will bypass and out in an even bigger oil to air cooler


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## Aussie (Sep 16, 2012)

pandrad61 said:


> this is the reason i bypassed the in radiator oil to water cooler on my grand cherokee. its another point of failure to get coolant in a slush box and BOOOOMMM!!!!. as you stated its actually more of a heater lol. once my warrenty is out i will bypass and out in an even bigger oil to air cooler


I had a radiator oil cooler fill the transmission with radiator fluid in a Falcon station wagon I used to own. Luckily it was a cheap transmission to recondition and I just had an external oil cooler fitted and sealed the outlets from the radiator. I never had another problem after that. At least with the gearbox or radiator, the rest of the car was a heap of rubbish.


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## KpaxFAQ (Sep 1, 2013)

Some more...this is how my outdated completely different transmission worked so it must apply to everything. Modern autos are designed to run at higher temperatures. Occasionally draining and filling is the best way to keep it healthy IMO. Luckily it's really easy on this car even though it doesn't appear to be at first. 

PS. This transmission does not have a filter.


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## Aussie (Sep 16, 2012)

KpaxFAQ said:


> PS. This transmission does not have a filter.


Does this also apply to the 6T45 transmission in my CTD, I really have no idea as this is much different to the older cars I have owned.


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## outdoorjr (Jan 17, 2016)

pandrad61 said:


> you do realize that the cruze diesel already has a external oil to air tranny cooler that is actually very big


I guess I am old school guy who thinks it does not have one. Ha. Then the temp should be much lower. I will have the transmission service, drain and fill with amsoil to see if temp goes down a little bit. I can not believe that transmission does not have filter.


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## outdoorjr (Jan 17, 2016)

pandrad61 said:


>


Thanks for the diagram. Saw diagram on other link showing this on the top of radiator. Hmm. I am still not comfortable seeing 220 degrees on highways where outside is at 60 degrees. I respect folks who thinks 220 is fine but for me it's a no.


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## pandrad61 (Jul 8, 2015)

> I guess I am old school guy who thinks it does not have one. Ha. Then the temp should be much lower. I will have the transmission service, drain and fill with amsoil to see if temp goes down a little bit. I can not believe that transmission does not have filter.


You have to remember this is not only a trans but a trans axle. its the heat of the engine, the tranny and differential all in one very tight area that is covered by panels to help with airo dynamics vs bay cooling, these type of FWD set ups are naturally gonna be more heat soaked and heated then a ol longitudinal set up


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## Robby (Mar 1, 2013)

New designs, by intent, have the trans fluid operating at close to coolant temperature and honestly, 250 degrees is meaningless to any lubricant.

The Cruze has a trans filter but it not serviceable.....the trans case has to split open to get to it.
It is rather large and considered a life of trans component.
I don't think I've seen any debris buildup in a trans (a healthy trans) in well over fifteen years.....these new fluids, mineral and synthetic alike, are very tolerant of the conditions found in FWD units.....it particular, the final drive......something fluids of the past never had to contend with.

I am a fan of fluid changing, just a drain and fill to recharge the detergents and friction modifiers, at 50k intervals if your plans are long term ownership.
I am not a fan of overcooling, or, what I call, trying to out engineer a engineer.......that air to oil add on cooler that came standard is plenty of cooling for this little trans.

Since the torque converter is generally in lockup over 30 mph, the only heat producer is the shearing effect of the planetarys and final drive.

Now, if you are planning on pulling a small trailer or some serious weight, I would likely change my tune if over 1000 lbs. (unwise over 1000 lbs. though.....it ain't a truck).

Rob


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## 1877 iris ave (Sep 23, 2011)

Which line is carrying fluid from the transmission to the cooler? The one which has 10,11,12 written next to it or the one that has 6,7,8,9 next to it?


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## boraz (Aug 29, 2013)

1877 iris ave said:


> Which line is carrying fluid from the transmission to the cooler? The one which has 10,11,12 written next to it or the one that has 6,7,8,9 next to it?


2014 Chevrolet Cruze Parts - GM Parts Department: Buy genuine GM auto parts & aftermarket accessories at wholesale prices.


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## pandrad61 (Jul 8, 2015)

> I am not a fan of overcooling, or, what I call, trying to out engineer a engineer.......that air to oil add on cooler that came standard is plenty of cooling for this little trans.


while do agree here, we are trying to out engineer the bean counter lol :wink:. cooling like brakes and tires is an area that i like to go above and beyond. if it where up to the engineers i bet we would never do the stupid in radiator cooler and would have a massive oil to air cooler if not for the accountants saying to save some cost and use a in rad cooler.

if your brakes stop fine with oe why not use better pads/rotor combo with better brake fluid, yes the walmart tires will do by why not run the bridgestone potenzas for the extra performance and safety, yes cooling system is sufficient but why not give it so much cooling capacity you will never under extreme conditions get close to heat out put to cooling capacity limits.


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## Aussie (Sep 16, 2012)

pandrad61 said:


> while do agree here, we are trying to out engineer the bean counter lol :wink:. cooling like brakes and tires is an area that i like to go above and beyond. if it where up to the engineers i bet we would never do the stupid in radiator cooler and would have a massive oil to air cooler if not for the accountants saying to save some cost and use a in rad cooler.
> 
> if your brakes stop fine with oe why not use better pads/rotor combo with better brake fluid, yes the walmart tires will do by why not run the bridgestone potenzas for the extra performance and safety, yes cooling system is sufficient but why not give it so much cooling capacity you will never under extreme conditions get close to heat out put to cooling capacity limits.


This is why the radiator is so efficient. I had only been driving for a couple of minutes when I took this picture (I parked first btw) which is why my DIC only shows 52, it normally runs at 84 summer or winter.
View attachment 177049


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## KpaxFAQ (Sep 1, 2013)

Robby said:


> New designs, by intent, have the trans fluid operating at close to coolant temperature and honestly, 250 degrees is meaningless to any lubricant.
> 
> The Cruze has a trans filter but it not serviceable.....the trans case has to split open to get to it.
> It is rather large and considered a life of trans component.
> ...


It does not have a true transmission filter, it has a basic pickup screen. Not a filter, basically just to catch any large initial break in debris.


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## outdoorjr (Jan 17, 2016)

This is a OEM GM part - Transmission cooler that came in with the car that came off the factory. It looks so small! Running at 220 degrees is still annoying me. I ordered a Hayden Cooler 677 and going to install it. I will let you know the results as well replace with transmission fluid Amsoil.


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## pacolino (Aug 1, 2015)

Budy, no offence but do you know better job than GM engineers?

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## IndyDiesel (May 24, 2015)

Sometimes knowing more much information is NOT A GOOD THING. I have a scangauge for my diesel, only reason I purchased was to know regen info to try and avoid shutting car down just prior to regen. I am not concerned about transmission temperature. I haven't read on the forum of ANY diesel Cruze transmission failure. Thinking you know more than the engineers that designed the transmission is just worrying about something that is not necessary. If you change transmission fluid as often as you say at 30k miles, I can't imagine ever having a problem. I think you could possibly do more harm than any possibility of good.


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## pandrad61 (Jul 8, 2015)

outdoorjr said:


> is a OEM GM part - Transmission cooler that came in with the car that came off the factory. It looks so small! Running at 220 degrees is still annoying me. I ordered a Hayden Cooler 677 and going to install it. I will let you know the results as well replace with transmission fluid Amsoil.


i for one support you trying to add some additional trans cooling. there is no down side unless you f up install. a cooler trans is always a good thing. keep us posted


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## outdoorjr (Jan 17, 2016)

I had a 1995 Suburban and the transmission went bust at 85K with out tranny cooler. It does not mean I am better than GM engineers. When I got 2005 Chevy Colorado Crew Cab, of course I added tranny cooler. Decided to trade in for 2007 Chevy Avalanche, of course I added tranny cooler. I always get all vehicles tranny fluid replaced at every 30K. So running at 220 degrees that concerns me no matter what. It does shorten fluid's lifespan if runs hotter. I am sure that you would be very concern if child has a fever at 105 degrees. So by having more information is better. ;-) I give children plenty of love and when they get older, they will give me plenty of love. I take care of children at young age and they will have their turn to take care of me when I get older. (hopefully they don't sent me to nursery home!) Same love for vehicles too. Right?


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## IndyDiesel (May 24, 2015)

outdoorjr said:


> I had a 1995 Suburban and the transmission went bust at 85K with out tranny cooler. It does not mean I am better than GM engineers. When I got 2005 Chevy Colorado Crew Cab, of course I added tranny cooler. Decided to trade in for 2007 Chevy Avalanche, of course I added tranny cooler. I always get all vehicles tranny fluid replaced at every 30K. So running at 220 degrees that concerns me no matter what. It does shorten fluid's lifespan if runs hotter. I am sure that you would be very concern if child has a fever at 105 degrees. So by having more information is better. ;-) I give children plenty of love and when they get older, they will give me plenty of love. I take care of children at young age and they will have their turn to take care of me when I get older. (hopefully they don't sent me to nursery home!) Same love for vehicles too. Right?


With all due respect, 220 tranny temperature has NO CORRELATION to a child with a 105 degree temperature. I don't like failure of major components either, you have a 100k mile warranty on a gm transmission for 5 years. Change the fluid and quit worrying about what COULD happen.


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## IndyDiesel (May 24, 2015)

You might ask your local Chevy dealer if you install a tranny cooler if that has any impact on your transmission warranty? I don't know if it does or not. If it doesn't lower tranny temp might be better. I have an engineering degree, you really don't know what the transmission is designed to run temperature wise. I don't either. Changing the fluid every 30k miles is a great thing and is 15k miles sooner than the severe maintenance schedule. Many years ago I had a transmission failure but I have zero worries about that today. A suburban is very capable of towing something our Cruze diesel isn't really designed for that. In my mind guessing what the transmission temps should be is based upon what? If you know what the tranny is designed to run at please share specifics.


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## diesel (Jun 8, 2013)

I will be the guinea pig for fully stock transmission life. 155K miles and so far still shifts like new. I did swap fluid out for Amsoil around 120K miles (2 years) though.


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## gtp1340 (Feb 16, 2016)

Transmission oil has limits temp wise. Heat kills any transmission . I have rebuilt a few FWD 4t65s and heat and lack of maintenance .One of the biggest problems is the valve body metal to metal contact . The material is non harden aluminum . And it will get a wear pattern over time and leak!! Causing many problems low pressure . Late shifts ,no movement ,broken accumulator springs . Ect . So swap to amsoil ASAP trans cooler !!


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