Gearboxes and oil servicing

Gear oil (aka transmission fluid) lubricates all the moving parts of manual and automatic gearboxes. In an automatic gearbox, it also has to convey heat away from friction parts and work with power transmission in the turbine between the engine and the gearbox.

Different boxes – different oils

Each gearbox has special requirements regarding the oil used and thus several different types of oils are used. For automatic boxes, different kinds of automatic transmission fluid (ATF) are used. For manual boxes, everything from normal engine oil to ATF is used. Normal engine oil is also available with different properties. Follow the manufacturer’s instructions as the oils have different properties.

Is servicing in accordance with the manufacturer’s recommendations necessary?

Yes, absolutely. This applies whether you have a manual box or an automatic one. Most manufacturers recommend service intervals of around 50,000 km (31,000 miles). For some automatic boxes, no service interval is specified since the oil is supposed to last for the entire service life of the car. Changing the oil more frequently than specified is never a bad thing.

Why does gear oil need to be changed?

Manual gearboxes: The problem with manual boxes is that the oil becomes mixed with metal particles which arise when bearings, synchronisation rings, and cogwheels wear down. These particles are very small, but they still mean that the lubrication provided by the oil is considerably worse.
 

Automatic gearboxes: An automatic gearbox generates a lot more heat than a manual one. Thus, the oil has to deal with a heavier load and finally loses its properties. Just as in a manual box, the oil becomes mixed with particles resulting from wear, entailing that the lubrication it provides is considerably worse.

What happens if the oil isn’t changed?

Without oil servicing, the gearbox will end up being lubricated by metal shavings (which arise during driving), instead of clean oil, thus reducing the service life of the gearbox. A costly gearbox replacement can then be on the cards unnecessarily prematurely. Regular servicing is, in other words, a good investment.

Is the quality of the oil important?

Yes, without doubt. Gearboxes make heavy demands on the oil used. If the quality of the oil is inferior, automatic boxes will wear out more quickly and run the risk of not working properly. Using oil which is better than that recommended by the manufacturer reduces fuel consumption and prolongs durability. The quality of the oil can be further increased by using the correct additives, e.g. using products made by Lubegard.

Do you need to do anything between services?

Yes, you have to check the oil level. Have your repair shop check the oil level in the gearbox during each "normal" service.

Oil servicing as a problem solver?

Certain types of problems arise due to poor quality oil. Most repair shops thus try an oil service before replacing a gearbox. Read more in "Tip! Solve gearbox problems".

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