Gearbox oil coolers

[Scannyman]

Hi Guys
I pull a large single axle caravan with an Audi SQ5 3ltr Bi-turbo diesel.
My concern is the gearbox oil which I know can take a hammering when towing and I am wondering if fitting an aftermarket additional oil cooler is worth the expense and trouble. My gearbox is the 8 speed ZF unit and only genuine oils are used throughout.
Any thoughts would be welcome.

 

[otherclive]

Some BMW models required an oil cooler to be fitted for towing, but never heard it for Audi. What rating for towing is the car, and what is the caravan max weight. Does your owners manual say anything?
What I’ve found on my cars is a caution in the Owners Manual saying something like oils to be changed if towing under arduous duty, or hot environments. Very informative as it’s up to the owner to decide.
I’ve never changed gearbox oil on account of towing, more because I don’t believe “ filled for life” is necessarily compatible with long life. I would do that even if a car wasn’t used for towing.
Has your car ever showed a gearbox oil temperature warning when towing up prolonged inclines in hot weather, like driving to the south of France in July?

My thoughts are that a car such as yours would not require an additional oil cooler but perhaps best to ask Audi Technical as they know the vehicle capability.

 

[GaryB]

When I looked at Audi's a few years back (as a company car) there was an option on the list that was ticked by default called "trailer towing prep" (or similar) which didn't mean it had a tow bar but it meant it had the necessary cooling upgrades to make it suitable for towing. As above, some manufacturers (Mercedes and BMW are two I know of) specify some cooling upgrades if an aftermarket tow bar is fitted, with the C Class Mercedes it was a cooling fan upgrade rather than anything for transmission cooling.

A phone call to an Audi service department might be useful as they will be able to advise if a cooling upgrade option is available, but the days of aftermarket cooling kits being available as a retro-fit have gone and personally I wouldn't fit one unless advised by the manufacturer as fitting one could well give them reason to void any future warranty claims.

 

[Jcloughie]

I pulled a large single axle with a 2 litre Volvo. But they used an Aisin torque converter gearbox. This was sealed for life. But some people recommended a oil change if towing. An oil change is amazingly wasteful in new (expensive) oil.

I did not change the oil and had no problems at all. Perhaps luck was involved. It had done 85,000 when I sold it.

Perhaps one type of box might be better than the other, I don’t know. Certainly dual cluch boxes have made very big improvements.

It may depend on what milage is, and has been done in the car, and how many towing miles are done each year. As well as some research on that type of box.

John

 

[Dustydog]

My VW Touareg uses the same gearbox as your Audi. Basically the same vehicle under the skin. I definitely have a transmission oil cooler. There’s nothing in the VW handbook that says an additional cooler is required. I tow a heavy TA no problems. Best check with Audi if you are unsure

 

[Jcloughie]

A little off-topic, sorry. In about 1988 I had a manual 1.9 non-turbo Citroen BX. There was an extra cooling kit from Citroen for towing. I bought and fitted it. Which meant moving the radiator fan to one side and fitting a second fan. Complete kit with wiring harness and a warning light to say it was operating.

I towed to the Baltic coast in very hot weather, being underpowered, I was flat out all the way.

After that expense, neither the original fan nor the extra fan ever came on.

John

 

[Dustydog]

A little off-topic, sorry. In about 1988 I had a manual 1.9 non-turbo Citroen BX. There was an extra cooling kit from Citroen for towing. I bought and fitted it. Which meant moving the radiator fan to one side and fitting a second fan. Complete kit with wiring harness and a warning light to say it was operating.

I towed to the Baltic coast in very hot weather, being underpowered, I was flat out all the way.

After that expense, neither the original fan nor the extra fan ever came on.

John

In those days it must have had a manual switch 😛😛😛

 

[Jcloughie]

In those days it must have had a manual switch 😛😛😛

No, it was thermostatically controlled. I think it took its signal from the original thermostat. I fitted an aftermarket kit to a Scorpio diesel some years later. That car was always overheating even with both fans on. On that one a probe was put into the top of the rad.

Like this.



John

 

[Dustydog]

No, it was thermostatically controlled. I think it took its signal from the original thermostat. I fitted an aftermarket kit to a Scorpio diesel some years later. That car was always overheating even with both fans on. On that one a probe was put into the top of the rad.

Like this.

View attachment 4964

John

I was joking😜😜

 

[Jcloughie]

I was joking😜😜

Went over my head. A bit too difficult for me, but I have got there now. 😋

John

 

[JTQ]

If the Audi, or other vehicle is factory built to tow, ie all if any mods are included at build then in our ambient IMO we need do no more.
The dangers are taking vehicles post build and simply adding tow bars, without all if any of the factory build kit the factory believes is required for towing.
The only slight saviour here is we are not the hottest most mountainous of countries, so what is required "there" might not be as needed here.

 

[RogerL]

Hi Guys
I pull a large single axle caravan with an Audi SQ5 3ltr Bi-turbo diesel.
My concern is the gearbox oil which I know can take a hammering when towing and I am wondering if fitting an aftermarket additional oil cooler is worth the expense and trouble. My gearbox is the 8 speed ZF unit and only genuine oils are used throughout.
Any thoughts would be welcome.

Trust the engineers!

I tow with a VW Touareg 3.0 TDi which shares a platform and the basic engine with the SQ5 (and others) - the transmission fluid is heated and cooled by the engine coolant and is quite adequate to tow 3500 kg in much warmer climates than the UK.

 

[JTQ]

Trust the engineers!

Thats assumes they have the last call on what the company's technical policies available in the public domain can state!

 

[Dustydog]

See Clive’s #2. Before I bought the Touareg we looked closely at the BMW X5. Allegedly born out of BMWs time when it owned JLR, taking the best of the old 4x4 s and creating Germanic reliability. What we discovered didn't sit well with me. Why should the massive X5 oem not be able to tow without modifications to the coolant system?
The modification was not cheap.
Thus VW won the day and performs effortlessly towing. Rightly or wrongly I got the feeling the X5 was under engineered or if you like all looks and no substance?

 

[GaryB]

See Clive’s #2. Before I bought the Touareg we looked closely at the BMW X5. Allegedly born out of BMWs time when it owned JLR, taking the best of the old 4x4 s and creating Germanic reliability. What we discovered didn't sit well with me. Why should the massive X5 oem not be able to tow without modifications to the coolant system?
The modification was not cheap.
Thus VW won the day and performs effortlessly towing. Rightly or wrongly I got the feeling the X5 was under engineered or if you like all looks and no substance?

BMW were pushed on that one and (according to one of the caravan magazines) they now quote two towing limits, 3500kgs with a factory fitted tow bar and 1900kgs if an aftermarket one is used. I have no idea how that is reflected on the VIN plate!

 

[Dustydog]

BMW were pushed on that one and (according to one of the caravan magazines) they now quote two towing limits, 3500kgs with a factory fitted tow bar and 1900kgs if an aftermarket one is used. I have no idea how that is reflected on the VIN plate!

Is Factory fitted at the factory or dealer?
I knew extra coolant stuff was needed but didn’t appreciate an aftermarket tow bar is restricted to 1900kgs!

 

[Scannyman]

Some BMW models required an oil cooler to be fitted for towing, but never heard it for Audi. What rating for towing is the car, and what is the caravan max weight. Does your owners manual say anything?
What I’ve found on my cars is a caution in the Owners Manual saying something like oils to be changed if towing under arduous duty, or hot environments. Very informative as it’s up to the owner to decide.
I’ve never changed gearbox oil on account of towing, more because I don’t believe “ filled for life” is necessarily compatible with long life. I would do that even if a car wasn’t used for towing.
Has your car ever showed a gearbox oil temperature warning when towing up prolonged inclines in hot weather, like driving to the south of France in July?

My thoughts are that a car such as yours would not require an additional oil cooler but perhaps best to ask Audi Technical as they know the vehicle capability.

My Audi is rated at 2000kg and van is 1400kg fully laden.
I totally accept what you say about long life / sealed for life type oils as No oil is that good.
No, I have not had any gearbox temp warnings or any warnings for that matter when towing.
Wouldn't do any harm running it past Audi technical.
Thanks for you advise.

 

[otherclive]

My Audi is rated at 2000kg and van is 1400kg fully laden.
I totally accept what you say about long life / sealed for life type oils as No oil is that good.
No, I have not had any gearbox temp warnings or any warnings for that matter when towing.
Wouldn't do any harm running it past Audi technical.
Thanks for you advise.

With your caravan weight I think you might be hard pressed to see any significant increase in gearbox oil or engine oil temp from such a capable powertrain. But no harm in asking Audi technicals advice.

 

[JTQ]

BMW were pushed on that one and (according to one of the caravan magazines) they now quote two towing limits, 3500kgs with a factory fitted tow bar and 1900kgs if an aftermarket one is used. I have no idea how that is reflected on the VIN plate!

Surely the factory would know what vehicle they made and put the correct VIN plates on them?

Those they build to towing spec a plate reflecting the 3500kg in the GVW, those they did not install the tow pack a VIN reflecting just the 1900kgs.

 

[GaryB]

Surely the factory would know what vehicle they made and put the correct VIN plates on them?

Those they build to towing spec a plate reflecting the 3500kg in the GVW, those they did not install the tow pack a VIN reflecting just the 1900kgs.

I’d certainly think so, but never seen one. Not sure if you could get it upgraded if you had the whole “factory fit” system fitted by a dealership afterwards but I doubt it.

Is Factory fitted at the factory or dealer?
I knew extra coolant stuff was needed but didn’t appreciate an aftermarket tow bar is restricted to 1900kgs!

My previous BMW520D and a C Class Mercedes estate were factory fitted rather than dealer fitted.

 

[PTA]

See Clive’s #2. Before I bought the Touareg we looked closely at the BMW X5. Allegedly born out of BMWs time when it owned JLR, taking the best of the old 4x4 s and creating Germanic reliability. What we discovered didn't sit well with me. Why should the massive X5 oem not be able to tow without modifications to the coolant system?
The modification was not cheap.
Thus VW won the day and performs effortlessly towing. Rightly or wrongly I got the feeling the X5 was under engineered or if you like all looks and no substance?

I too have a Touareg (my third). If an aftermarket tower is fitted VW indicate that an upgraded engine cooling fan should be fitted. Online forums state that, in the event of engine damage caused by the lack of upgrade, the warranty will be invalidated. However, I have towed a 1650 MTPLM caravan to Spain and Portugal, in midsummer, over the past ten years. The temp gauge has never moved normal at any time.

 

[JTQ]

I too have a Touareg (my third). If an aftermarket tower is fitted VW indicate that an upgraded engine cooling fan should be fitted. Online forums state that, in the event of engine damage caused by the lack of upgrade, the warranty will be invalidated. However, I have towed a 1650 MTPLM caravan to Spain and Portugal, in midsummer, over the past ten years. The temp gauge has never moved normal at any time.

For clarification:

1. Has yours the factory modifications?
2. Does your quoted "temp gauge" actually look at this thread's subject issue, the "gear box oil cooling"? I suspect it only monitors the engine coolant temperature?

 

[Dustydog]

PTA got me investigating. This is the first I’ve heard about cooling system changes when towing.
I found this but all a bit late for me

VW Touareg owners

Hi, Some of you may recall previous discussions regarding post 2011 models without the factory fit towbar and uprated cooling fan. For those buying a new car, the approximate £750 for the factory-fit uprated cooling and towbar was a no-brainer. However, buying second hand and being...

www.caravanclub.co.uk

The only difference I can ascertain is the fan motor’s wattage. 650 w V 850 w.
Mine is out of warranty, I’ve towed with her for four years, including some very long 58 mph tugs . The temp gauge has never caused me concern , no warnings on oil temp .
Is a 850 w motor really going to achieve a significant higher RPM than its sibling?
I doubt the fan runs all the time, it doesn’t!
Should I be worried?
A quick look this morning at the handbook reveals nothing, will dig deeper.

 

[JTQ]

Should I be worried?

If as we are told the basic vehicle tows 1900 kgs and the up speced 3500 Kgs, then with most UK vans I doubt their is an issue; look at your VIN plate and work out your basic towing capacity, subtracting the max vehicle weight from GTW.

A high Wattage fan will not necessarily turn faster, simply be of a design to shift a bigger mass flow of air through the rads.
The engine coolant temp is likely a monitored value, so if that's "happy" then the engine is within what VW tolerate.

The gearbox oil cooling is IMO going to be more challenged with hard climbing, heavy loaded towing, multi gear change use in a very hot ambient, with lowish vehicle speeds; not really a UK like situation.

Though not ZF, if the auto they use is like that box, the gearbox electronics will look after over heating and back off what the engine can stuff out and the ratios in use to try and protect itself. I suspect yours will also feature those basic protections.

 

[GaryB]

The first time I discovered this was AFTER ordering a Mercedes C220 estate (manual) in 2010 (company car), my allowance didn't cover adding a factory tow bar so I had one retro-fitted. In the small print in the manual it had a sentence stating "additional cooling might be necessary if towing a trailer without a factory fitted system". I enquired at a local dealership as a friend worked in the service department and he eventually found the parts list for the upgrade, similar to VW, it included a replacement fan AND underbody ducting. He commented that they sometimes fitted tow bars to cars as part of a sale and they had never ordered/fitted the cooling kit and that unless towing through The Alps in the height of summer it was perhaps over-kill. I towed with that car for three years/80,000 miles with no ill-effects. However, where possible, I now opt for a genuine tow bar/electrics, fortunately my last two cars have been Volvo's and don't require any additional cooling.

I do wonder why some manufacturers skimp here? While "every penny counts" I really can't see the difference between two fans making much difference to the overall cost. On the other hand, in my previous job the engineer's bonuses often had a percentage relating to cost saving initiative they'd found so it might well be connected!