Automatic transmission oil cooler - do I need one?

Mike Harding · Guru

Automatic transmission oil cooler - do I need one?

Possum3 · Guru

I would have thought if you are only puttering around and not doing mountains, No. If you are going on long drives working the new beast up, down hill and dale, Yes.
It is specified as a 3 tonne towing with a six speed auto so I would leave it as designed. The only way to determine if cooler needed, is by keeping an eye on transmission oil temperature. If it ain't broke don't fix it.

Greg 1 · Guru

Check the owners handbook. It usually advises if additional coolers are required when towing. Otherwise ask at your dealerships service dept.

Mike Harding · Guru

Greg 1 wrote:
Check the owners handbook. It usually advises if additional coolers are required when towing. Otherwise ask at your dealerships service dept.

I did.

It doesn't.

Which is why I am asking here.

iana · Guru

My suggestion would be to first invest in a "Scan Gauge" and monitor what the transmission temperatures doing. I think excessive temperatures may be linked to the right foot. You will soon see if the temperature rises to a level you are not comfortable with.

-- Edited by iana on Friday 21st of February 2020 09:04:46 PM

rgren2 · Guru

Just do it.

Mike Harding · Guru

Buy Nike trainers you mean?

https://en.wikipedia.org/wiki/Just_Do_It

How will they help my automatic transmission fluid to stay cool?

Or perhaps you think the coolness of the trainers will do the job?

I didn't realise this question was so complex.

Whenarewethere · Guru

Doesn't the transmission lock up on these cars, to save fuel. Stick it is sports mode if they have this feature.

blaze · Guru

yes, no, maybe
until you have the correct temps, what is the normal temp,
what is the max temp for the brand of oil you are using,
No one can give you an answer, its all here say.
Not trying to be flippant but you do need to know.
With my autos I would change the oil every 30000km and have done it ar 15000 after some hard work
cheers
blaze

Jaahn · Guru

iana wrote:
My suggestion would be to first invest in a "Scan Gauge" and monitor what the transmission temperatures doing. I think excessive temperatures may be linked to the right foot. You will soon see if the temperature rises to a level you are not comfortable with.

_____________________________________________________________________________________________

Hi Mike smile

iana has a good suggestion here which I fully agree with. You can also monitor other operating paramenters too if you need some feedback on other things.

What temperature to look for as excessive. Well that's easy. You look at it as you drive normally and get the feel of what is normal, without and with the van. I would expect around 85-95. Then you push it a bit and see what it goes up to, possibly 100-105. So if it goes more than that in some situations then back off or take a rest. Not rocket science. My

Jaahn

woofta and precious · Senior Member

Tow my 2.5 tonne van with a Trailblazer Auto.
I use it in manual mode, and never go into 6th gear. Sit on about 100 kmh (gps speed) and get around 14 - 15kpl.
I have not had any problems after 3 and a half years.

Mike Harding · Guru

Sorry guys, I should have been a little clearer.

The Trailblazer has both an auto transmission fluid and coolant readout on its "car computer" and I have a Bluetooth OBD2 reader and Torque on Android - when I can find the damn OBD2 socket! :)

This issue is more complex than I had realised and gearbox ratios and torque converter lock-up come into the picture more than I had realised.

Both W&P below and e-mails indicate towing in manual is preferable and I suspect avoiding gear 6 always and 5 mostly may be a good strategy but, as others have said, there is going to be some trial and error involved but, hopefully, not too much error :)

JackoFJR · Senior Member

rgren2 wrote:
Just do it.

What rgren2 , said

-- Edited by JackoFJR on Saturday 22nd of February 2020 05:10:34 PM

Mike Harding · Guru

JackoFJR wrote:
rgren2 wrote:
Just do it.
What rgren2 , said

Would either of you care to offer a supporting argument as to why I should "just" spend $2000 on a transmission oil cooler?

iana · Guru

Just to show, I have the scan gauge mounted on top of the instrument panel, just lower than line of sight, KPH, Automatic Transmission Temp, Battery volts and coolant temp. I find the KPH the handiest.

It is just stuck to the coming with Velcro tape.

iana · Guru

Just a point to remember, the oil cooler is (normally) mounted at the front of the vehicle, if you haven't a bull bar fitted, and you hit a kangaroo, that's your trip over, if the cooler is damaged. But yes some affirmative reasons for the cooler would be good.

outlaw40 · Guru

Iana plenty of other thing can end your trip . Mike Harding the only way to tell will be to monitor trans temps, some vehicles are happy with the oem cooling system while some struggle , it can be a very vehicle specific issue by that i mean 2 identical vehicles can differ . in my case with the bt50 i had a 2016 and have in the last 12 months change to a 2019 , both identical in every way including all accessories. the only difference is the colour . the 2016 never had an auto temp issue but the 2019 does and i will be fitting a cooler to it as it definitely needs it . all temps were read with the same scanguage . so to put it simply monitor temps ask a reputable transmission expert what temp you are aiming for then make a decision. also if you intend to keep the vehicle keep in mine you may be shortening the life of the transmission by running it hot and warranty runs out someday you may have to wear the repair bill .

patrol03 · Senior Member

The oil cooler is mounted in front of the radiator behind the grill.I am sure if you hit a kangaroo with sufficient force not only your oil cooler would be damaged but also the aircon condenser and the radiator together with its fans.

Over a period of 50 years towing caravans I have always fitted an oil cooler to the transmission if it was an auto. Most car manufacturers run the auto trans fluid through the radiator tank for cooling. For this reason if none other, if you use your vehicle for towing a caravan it would be an extremely wise choice to fit an AT condenser. Most modern radiators run at high temperatures and it is the chemical coolant, the pressure cap, and the air flow through the fins that prevent the liquid coolant from boiling. Larger radiators with extra fins to increase cooling surface area, and sometimes an extra row of tubes are more efficient cooling elements.

So tackling steep climbs, slow heavy traffic, high atmospheric temperature,strong head winds and or any combination of these situations, the coolant temperature rises and heats up the auto trans fluid and conversely the increased work effort of the AT is heating up the radiator coolant.

Smell and colour of AT fluid can indicate a hard working unit.

AT coolers come in various sizes. Some come as an ordinary condenser while more sophicated units come as a condenser and thermo controlled unit.
In terms of AT rebuilds particularly in 4WD vehicles the cost is chicken feed. Check them out on the internet.There are plenty for sale new on e-bay.

The extra AT radiator can be fitted either of two ways. After the radiator and on the return pipe to the AT or by completely bypassing the radiator.

The preferred preference, providing the new unit has sufficient capacity for the vehicle use intended is the by-pass method. Some larger 4WD vehicles have this method as standard.

In my own Patrol the AT cooler is completely separate in fact it also has an AT heater to enable the AT fluid to reach running temperature quickly. Being over cautious I change my AT fluid annually which would represent about 8k towing in a total of 15K per year.

Jaahn · Guru

outlaw40 wrote:
----------------in my case with the bt50 i had a 2016 and have in the last 12 months change to a 2019 , both identical in every way including all accessories. the only difference is the colour . the 2016 never had an auto temp issue but the 2019 does and i will be fitting a cooler to it as it definitely needs it . all temps were read with the same scanguage .--------------

______________________________________________________________________________________________________________________________________

Hi Outlaw40 smile

Just a comment on this. The Scangauge does not measure the temperature directly but reads out the value the ECU gets from the internal sensor (just as it does for all the other reading). So it may be that the there is a discrepancy between the temp sensors in the two vehicles. Or perhaps the oil flow control thermostat in the new one controls a bit hotter than the old one. Just saying this to point out how it works. aww

Jaahn

outlaw40 · Guru

Yes i fully aware how the system works .... which is why i say the choice to fit or not to tip should be made on a case by case basis .

JackoFJR · Senior Member

Mike Harding wrote:
JackoFJR wrote:
rgren2 wrote:
Just do it.
What rgren2 , said
Would either of you care to offer a supporting argument as to why I should "just" spend $2000 on a transmission oil cooler?

Yeah ok . My mates and I have had several 4wds autos fitted with Scan Gauges all autos can and will get hotter than they should in certain conditions towing , 4wding ect

Ask a auto trans specialist I bet they will say yes and not just to rip you off , 2 grand have you priced one that seems a lot , the last one I had fitted to a Dmax was a lot less than than , I cant remember how much

rgren2 · Guru

$2000, paying too much. How much for a new gearbox, getting towed, emergency accomodation. The costs soon add up. Also, dont forget peace of mind. Gearboxes can fail suddenly, either lockup of freewheel, now imagine both these scenarios and the reason the gearbox is overheating. Putting the cooler in series with the built in cooler would mean that any electronic controls wouldnt be affected, also gives the gearbox a bigger oil capacity. Win, win.

Mike Harding · Guru

Well! This subject is much more involved than I expected.

$2k was a pure guess, a little research indicates $1 or a little more is closer.

Then, of course, there is warranty; the vehicle has over four years manufacturers warranty left and you can bet if I fit an ATF cooler they'll refuse warranty on the gearbox and maybe engine too.

Having now done extensive research on the net there are two clearly opposed schools of thought: one says fit a cooler and the other says the original design is fine - neither school produces convincing supporting evidence. However having spent a working lifetime doing product design and having worked with two major vehicle manufacturers I consider it unlikely they would routinely specify their vehicles for something they cannot do and which would certainly result in many major and catastrophic failures. The one word no one in automotive design is allowed to utter is "Recall"!

Two days past I towed my 2.7T caravan from Melbourne to north central Victoria (about 275km) and it was a 36C day, this journey does not cover serious hills but it has a number of smaller ones. The ATF temperature peaked, once, at 96C and generally ran around 88C to 90C. I drove in manual using gears 4 and 5 and tried to ensure torque converter lock-up.

Yesterday I drove (vehicle only, no van and in 'D') 150km, no hills at all, and ambient was 32C, the ATF temperature was mainly stable around 85C.

For the moment I shall not fit an ATF cooler but I shall watch the ATF temperature like a hawk until I am fully confident of its behaviour.

Thanks everyone for your input.

iana · Guru

Hi Mike, yes the one thing not mentioned is the invalidating the warranty, the moment you fit a non manufactures' part, or do a modification not performed by them, any warranty issues then are passed to the third party supplier, that also includes the extended warranty if you have one.

I don't think there was a party saying don't fit a cooler, but rather try it and see, different driving styles, driving times e.g. middle of the day instead of early morning for example can make a difference. Can you stand slowing down, or not driving from dawn to dusk at top speed?, all of these factors make a difference, so everything is a variable, and you have to find out what works.

There is much scare mongering out there by those that are selling and fitting these coolers, one such statement " it will reduce the load on the transmission", the load on the transmission and the rest of the drive train will remain unchanged regardless of whether you have fitted a cooler or not, it will not give you a license to drive beyond the vehicle drive train abilities.

I myself will have to look at fitting some means to cool the transmission, so far I have been unsatisfied with what's offering. But I will keep looking and exploring.

Greg 1 · Guru

You can contact the manufacturer and discuss what they recommend and if they do a cooler kit for towing. If they do so then you have your answer but if they believe it unnecessary then try without it.

bobsa · Senior Member

Mike

8 Row Transmission Oil Cooler Manual-Auto Radiator Converter Kits Universal $69 ebay
maybe $200 to fit ( i put one on my BF falcon all good )

I put one on not for the over heating, it is for when the original heat exchanger bursts and
the dreaded milk shake happens ( water in the Trans ) . The BF falcons were renowned for this, a costly affair

They dont hurt to have them fitted and are good insurance , but at 15K on the clock I dont think yours is ready to fail
To protect your trans from over heat well depends how good the original is, only you can tell

Bob

-- Edited by bobsa on Tuesday 25th of February 2020 12:34:28 PM

-- Edited by bobsa on Tuesday 25th of February 2020 12:35:55 PM

ken thomas · Guru

2 of my friends have just had their trans fail at 100000 due to towing and the ford policy of not needing servicing for 10 years
I had mine first serviced at 67000 and the oil was burnt and just now had it serviced at 100000 and the oil was again slightly burnt and some metal filings in it.
I had the cooler and valve fitted and now bypass the heat exchanger
Cost was $1100
Ken

-- Edited by ken thomas on Tuesday 25th of February 2020 05:33:42 PM

Avaner · Newbie

Hi Mike, for what is worth, in my humble opinion it is worth the peace of mind to have than to have not. I tow a 2.5 T van and fitted a second cooler inline with the first.
I say second cooler because I went to the wreckers and purchased a genuine cooler from a wreck ($25.00) and fitted it in parallel with the original cooler. It`s situated on the opposite side to the original. (original left of radiator, second on right side of radiator behind the grill)
The only draw back here is you have to manufacture your own brackets, (not hard to do) Total cost was approx $40 bucks. I have done 60,000 k`s of towing with this setup and never had a problem. I always tow in the manual mode and never in top gear. I have tried towing in top gear, however my exhaust temp and gearbox temps go through the roof.

Hope this helps

Cheers

-- Edited by Avaner on Thursday 27th of February 2020 03:47:09 PM

Petesahut · Member

patrol03 wrote:
The oil cooler is mounted in front of the radiator behind the grill.I am sure if you hit a kangaroo with sufficient force not only your oil cooler would be damaged but also the aircon condenser and the radiator together with its fans.

Over a period of 50 years towing caravans I have always fitted an oil cooler to the transmission if it was an auto. Most car manufacturers run the auto trans fluid through the radiator tank for cooling. For this reason if none other, if you use your vehicle for towing a caravan it would be an extremely wise choice to fit an AT condenser. Most modern radiators run at high temperatures and it is the chemical coolant, the pressure cap, and the air flow through the fins that prevent the liquid coolant from boiling. Larger radiators with extra fins to increase cooling surface area, and sometimes an extra row of tubes are more efficient cooling elements.

So tackling steep climbs, slow heavy traffic, high atmospheric temperature,strong head winds and or any combination of these situations, the coolant temperature rises and heats up the auto trans fluid and conversely the increased work effort of the AT is heating up the radiator coolant.

Smell and colour of AT fluid can indicate a hard working unit.

AT coolers come in various sizes. Some come as an ordinary condenser while more sophicated units come as a condenser and thermo controlled unit.
In terms of AT rebuilds particularly in 4WD vehicles the cost is chicken feed. Check them out on the internet.There are plenty for sale new on e-bay.

The extra AT radiator can be fitted either of two ways. After the radiator and on the return pipe to the AT or by completely bypassing the radiator.

The preferred preference, providing the new unit has sufficient capacity for the vehicle use intended is the by-pass method. Some larger 4WD vehicles have this method as standard.

In my own Patrol the AT cooler is completely separate in fact it also has an AT heater to enable the AT fluid to reach running temperature quickly. Being over cautious I change my AT fluid annually which would represent about 8k towing in a total of 15K per year.

The above is good information, OEM cooling is simply a heat exchanger, not very efficient. I have been in the industry as a specialist for over 30 years, things have changed a lot since I was in business.

If fitting an oil cooler is not practical for whatever reason, then change your transmission oil somewhere in the area of every 20000k. It's the additives in the oil that break down with high heat, not the oil. Fresh oil helps considerably.

In the old days, the adage always was, if fitting a towbar, then an automatic transmission oil cooler should be fitted along with it. These days it's not always quite that simple. The only way you can determine how hot the transmission is to have some kind of temp sensor, how many modern vehicles monitor transmission temp, I really don't know.

outlaw40 · Guru

I would say all of them because if they weren't they wouldn't go into limp mode when they get to hot . scanguage 11 will tell the steering wheel attendant before this happens .