An automatic gearbox is a complex hydraulic system transmitting the engine power to the wheels, mainly by the oil it contains. Its quality and performances are therefore essential to ensure perfect operation, whatever the conditions, and also to promote longevity of the gearbox, a particularly expensive car part.
These lubricants are specific and can in no case be replaced by engine or manual gearbox oil. It should also be borne in mind that drain operations (every 20 to 60,000 km depending on the vehicle) require a minimum of knowledge and tools. It is therefore preferable to entrust this operation to a professional to avoid doing anything wrong. On the other hand, checking the level of an automatic gearbox is a simple operation to be made every 10,000 km. Refer to your car's manual for details on this operation. As a general rule, you must turn the engine on and place the speed selector at position 'P'.
Oil temperature also influences the level, so as a general rule you must carry out this check on a hot engine after it's been running for at least 10 minutes. For a precise check, first wipe the dipstick with a lint-free cloth, and also take care not to introduce any dirt into the hole.
If the level is insufficient, pour some Dexron Motul down the dipstick hole. Take care: a few millilitres is enough as a complement, as the total content of the gearbox is generally low.
High consumption of gearbox oil is abnormal. A level that has dropped is generally caused by a leak, which you must repair as soon as possible.
Power assisted steering
The power assisted steering of cars is generally hydraulic and requires, like automatic gearboxes, Dexron fluid, to operate correctly. This oil is therefore the same as that of automatic gearboxes but the two circuits are clearly separate.
The hydraulic system of power assisted steering comprises a little reservoir in the engine compartment. It is translucent with marks showing the levels or it has a dipstick incorporated in the cap. To check the level, the engine must be turned off