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Towing & Oil Cooling

Towing & Oil Cooling

Transmission overheating will cause Gearbox Failure. Oil Coolers are proven to reduce oil temp 25% - 30% when towing.

Picture the scene. It's the first bank holiday of the year, the forecast's good and hot so you squeeze the happy family and all the associated luggage into the car, hitch up the boat/caravan and set off for a relaxing weekend at the coast/in the country.

Twenty or thirty miles down the road you are stopped beside a busy dual carriageway with smoke rising from your now motionless car, having left a trail of oil and smoke on the road for the last mile or so. The now decidedly unhappy family looking accusingly at you as if it's all your fault because you said "it will tow it - no problem".

The garage arrives and declares the Automatic Transmission a write off and you are left wondering if the repair bill is going to be more than the car is worth. The family holiday in the Algarve is on the line and there are mutterings about selling the boat/caravan to pay for the repairs.

Not a pleasant scene is it? But it can, in most cases, be avoided by fitting a supplementary transmission cooler.

"But my car already has a transmission oil cooler", you say - "it shouldn't need another one". With the exception of some four wheel drive vehicles, that have substantial oil cooling as standard, all cars will need an extra cooler to prevent transmission overheat when towing.

Why does it get so hot?

If you were to tow with a manual car you would expect to wear out the clutches much quicker due to the extra effort required to get the car moving/up motorway gradients etc. with the increased weight. In an automatic all the extra effort is done mainly by the torque converter. This is the primary heat source in any automatic transmission and the effects of towing increase the heat produced dramatically. It is not at all uncommon for a car in the above situation to literally boil the oil in the torque converter, causing it to blow oil at any convenient point. Even if the oil is not getting as hot as this it will still be running much hotter than both it and the transmission were designed to. The effects of the transmission running hot is to harden the multitude of seals and O rings within the unit - leading to pressure loss and very premature transmission failure.

What about the Standard Cooler?

The standard cooler fitted to most vehicles for the last twenty years or so is the tubular oil to water type, fitted generally in the bottom tank of the radiator. When the radiator is new the cooling capacity of this type of cooler is adequate for solo motoring, but does not provide sufficient cooling when the vehicle is towing. With the engine having to work harder when towing so the temperature of the water in the radiator increases, exactly the opposite to what the cooler needs. Once the vehicle gets to be a few years old with several thousand miles behind it then this type of coolers efficiency drops to the point, in some cases, where it is doing virtually nothing at all. This is due to silt build up in the bottom of the radiator - all radiators suffer from this to some degree, and you don't need much in the bottom of the radiator before the cooler efficiency starts being compromised due to the restricted water flow around the cooler. It is not uncommon to find the cooler completely buried by this silt - hence no cooling.

So what is the answer?

To fit an additional transmission oil cooler that is designed specifically to address these problems.


Our nearest member to you will be more than happy to advise you, oil coolers are proven to reduce oil temperature 25% - 30% when towing.