How to change your automatic gearbox oil
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Automatic gearboxes don’t need an oil change, right? This rumour has been stubbornly going around for years but it simply isn’t true. Transmission oil has a natural ageing process just like anything else – crucial additives are lost or the oil simply becomes less effective at lubricating and needs replacing to prevent damage to the gearbox and to keep your changes smooth as silk.
So, now you know you do have to change your oil, what’s the best way to do it? Well, Hamburg-based spare parts manufacturer MEYLE has given us this four-step guide, and a handy video to explain all.
The oil change shown and explained here is for a Mercedes Benz 7G Tronic transmission, so the process could deviate depending on the make and model you have.
Step 1: Preparation
Before starting, the engine must be warmed up to operating temperature (the coolant should be 80 degrees Celcius or above), the gearbox set to N and the ignition off. Then use a four-post lift or lift platform to raise your car while keeping it level. This is the only way to ensure correct filling and oil level measurement.
Step 2: Drain the old gear oil
On some (but not all) gearboxes the additional oil pump can be drained. To do this, first loosen the plug of the additional pump. Then remove the drain plug and drain the used transmission oil. After opening the drain plug, the overflow pipe seal needs to be broken to ensure all the oil is drained.
Next, remove the additional oil pump of the automatic transmission and allow the remaining transmission oil to drip out. After the oil has been drained completely, turn the engine in the direction of rotation to reach the drain plug of the torque converter. Now unscrew the converter drain plug and drain the remaining transmission oil. Once this is done, retighten the M8 drain screw and tighten it up to 10Nm.
Step 3: Replace the hydraulic filter
The next step is to remove the oil pan. Be careful – there will still be some residual oil in the pan.
Next, remove the old hydraulic filter and clean the oil pan. Then fix the seal and the magnets and install the new overflow pipe.
Now it’s time to insert a new hydraulic filter (available from the MEYLE-ORIGINAL oil change kit), and then re-attach the oil pan. Set your torque wrench to 4Nm and tighten the oil pan screws crosswise with a 180-degree angle of rotation. Please note that the oil pan screws can only be used once. Screws that have already been screwed on cannot be reused because they will break off.
The next step is to re-attach the holder of the shielding plate. Before the (if applicable) additional oil pump is refitted, the seal connections on the suction and discharge sides should be checked for damage and replaced if necessary. Then refit the additional oil pump and tighten to 8Nm.
Step 4: Top up gear oil
The final step is to refill the transmission oil. Fill the filling device with eight litres of new automatic transmission fluid and screw on the adapter for topping up the gearbox.
MEYLE can supply you with everything you need to change your transmission oil – choose from one of 60 different kits
Next, connect the pump hose, open the valve and fill with six litres. Then start the engine, engage gear P and connect the diagnostic device to determine the transmission oil temperature. As soon as the oil has reached a temperature of 45 degrees Celcius, the remaining oil should be filled while the engine is running.
When a constant flow of oil flows back at the specified oil temperature of 45°C, the correct level has been reached. Then remove the adapter.
Now shift the gears P-R-N-D for six seconds each with the engine idling, while at the same time applying the brake. Then bring the gear shift back to P.
Finally, close the filling opening with a new drain plug and tighten with 22Nm of torque – then you’re done.
To make the process easier, MEYLE sells more than 60 different oil change kits, which include all components for the oil change on automatic transmissions including filters, seals, screws, drain and/or inlet screws, magnets and the amount of transmission oil required depending on the application – perfect for workshops and drivers alike.
Note: Always follow manufacturer specifications and instructions.