Automatic Gearbox Fluids and Flushes

People often ask why an Automatic Transmission Fluid Flush or ATF flush is necessary?

The main problem is that the special ATF fluid gets worn out over time as any fluid or oil that is being used hard will. Land Rover say that the ZF6HP gearboxes are maintenance free and sealed for the life of the vehicle.

Common sense says that any fluid will wear out and need regular changing just like engine oil.

The ATF fluid is not just a lubricant, it transfers the power between the engine and the gearbox, so it has to meet certain friction specifications. The main reason that the ATF fluid gets worn out is overheating. For example, a Land Rover Discovery 3 or Range Rover Sport 2.7 TDV6’s engine has a standard output of around 190bhp and weighs the best part of 2.7 tons! Add on a heavy trailer or caravan and you soon realise what a tough job the gearbox fluid has to do and it cannot possibly last the lifetime of the vehicle.

Worn out, burnt ATF fluid loses its lubrication and friction properties, this can lead to mild gearbox problems such as torque converter judder, rough gear changing, fluctuating engine revs and will eventually lead to gearbox failure.

So why can you not just drain it from the sump and refill? The ZF6HP automatic six speed gearbox holds a total of 9.5 litres of ATF fluid. Out of this, approx 7 litres is held within the torque converter and cannot be drained by conventional methods.

JGS4x4 have invested in a state of the art Fortron ATF flush machine, this drains and replaces the ATF fluid whilst the engine and gearbox are running and replaces nearly 100% of the old fluid. A conventional drain and refill means you can only change 2.5 litres of fluid so in effect is only slightly diluting the old, worn out fluid.

It is now recommended that to preserve the life of the automatic gearbox, the fluid is changed between 85-100K miles. Obviously if the vehicle has done more mileage than this then changing the fluid must be a priority before any long term damage is caused to the torque converter or gearbox internals. But be aware that changing the fluid cannot reverse mechanical damage caused by worn out ATF fluid.

This photo shows the old, burnt, worn out ATF fluid from a Discovery 2.7TDV6 with 85,456 miles on the clock. You can see the new fluid on the right is opaque and has a light, golden colour and a thin viscosity. The old fluid on the left is black, burnt, smelly and is much thicker than it should be. Remember this is from a relatively low mileage vehicle, we have seen much worse from vehicles with 120-140K miles on the clock.

We can change the ATF fluid in just about any vehicle but we specialise in Land Rover’s so get in touch and book yours in now.


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