Your gear oil is constantly working to reduce the stresses placed on your gearbox, keeping it operating at its peak. But like most lubricants, it may eventually need to be changed, otherwise the slow accumulation of deposits can end up clogging your oil gearbox filter and potentially damaging its components, resulting in costly repairs.
In this guide, view simple, step-by-step instructions on when and how to check and change your gear oil and filter, ensuring your gearbox keeps working its best.
When should I change my gearbox oil and filter?
If your vehicle or machinery doesn’t have an oil life monitoring system that automatically alerts you when your gear oil requires changing, knowing when to change your gear oil and filter can be an imperfect science, but there are guides for different types of vehicles:
- Manual gearboxes usually require a gearbox oil change every 30,000 to 50,000 mi (48,000 to 80,000 km).
- Automatic gearboxes usually have gear oil change intervals of between 60,000 to 100,000 mi (96,000 to 160,000 km).
- It’s advisable that you change your gearbox oil filter at the same time as your oil.
- If you have a gearbox leak repaired, then always change your oil after the repair to ensure it’s fully topped up.
How to check gearbox oil level
Because these ranges are so large, a good way to gauge your oil health is to check its colour. New oils are brightly coloured (usually red) and semi-transparent, but as they degrade or accumulate deposits, they turn a darker shade, lose their transparency and can smell burnt due to oxidation.
To check your gearbox oil:
- Open the bonnet and locate the transmission dipstick (its location should be shown in your owner’s manual). If your model doesn’t have one, you will probably have to raise your car using a jack or lift, then carefully remove the transmission fill cap located on the transmission assembly.
- Pull the dipstick out of the filler tube. If you have raised your car, insert a ruler, screwdriver or other implement into the system to sample the oil.
- Check the colour of the oil.
If your oil is dark brown, black, or light pink (usually due to water contamination), then you need to change it. Red-brown, semi-transparent fluid is often slightly degraded, but doesn’t necessarily signify a need for a change.
How to change your gear oil
If you don’t have much experience in vehicle or machinery maintenance, it’s a good idea to get a professional to change your gear oil. If you want to do it yourself, follow these steps:
- If your vehicle or machinery has a drain hole, locate it and place a catch pan beneath it. If not, place a catch pan underneath the entire gearbox assembly.
- Unscrew the drain bolt or remove the gearbox pan, then let all the fluid drain into the catch pan.
- Remove the old gasket and filter, with replacement components to hand.
- Inspect the gearbox pan, cleaning the magnet of any small pieces of metal. If large fragments are present, your gears may be very worn and require replacement.
- Install the new gasket and filter, then bolt the pan back on to the machinery or vehicle.
- Get the right gear oil for your vehicle or machinery using the Total Lubricants Catalogue (after checking your owner’s manual for the type of fluid required) or use the LubAdvisor tool, navigating to your vehicle, clicking the blue ‘Select other component’ button, then the correct button for your type of gear assembly.
- Check how much fluid your gearbox requires in your owner’s manual.
- Put the correct amount of fluid into your gearbox using an oil pump or pour in the correct amount after measuring it out.
- Let the oil settle for a few minutes, then start the engine and run the vehicle for a short time.
- Check the oil level to ensure it’s correct (view the previous section of this article for instructions how).
- Dispose of the oil responsibly – find your nearest UK oil bank here.
These instructions are only meant as a guide – vehicles and equipment may be designed differently, so always check your owner’s manual. If you are unsure of how to change your gearbox oil, always use a professional.
