How to change your gearbox oil
Your gearbox oil is a vital component of your vehicle’s transmission system that helps everything to run smoothly – literally. Most of the time, all you need to do is check the level of gearbox oil to ensure it’s not running too low, as this can cause mechanical faults and serious damage.
But every once in a while, your gearbox oil will need to be replaced. That’s because tiny deposits of dirt and grime make their way into the oil, clogging it up and making it less effective. In time, this can affect performance and result in excessive wear and tear in your transmission system.
Below, we explain how to change your gearbox oil and how often it’s necessary to do so.
How to change the oil in your gearbox
Knowing the right method for changing your gearbox oil is key to doing it safely and efficiently so your vehicle stays roadworthy. So, when it’s time to get the job done, how exactly should you do it?
The first thing to remember is that these instructions are generalised guidelines. Different vehicles can be designed in slightly different ways, so if you’re unsure of what to do, consult the owner’s manual. Or, if you’d prefer to know the job’s in safe hands, take your vehicle to your local autocentre to have the oil changed by a professional.
If you want to change your gearbox oil yourself, here’s how:
Prepare yourself for a messy job
Changing gearbox oil can be a messy procedure, so it’s best to wear overalls or something you don’t mind getting dirty. Gloves can also be helpful for keeping your hands clean – and you may be best to remove any jewellery or watches on your hands and wrists before getting started.
Be sensible when working underneath vehicles. If you don’t have the proper personal protective equipment, it’s best to let a professional handle things.
Prepare your vehicle
Gearbox oil tends to drain more easily when it’s at operating temperature – in other words, the temperature it is after your car’s been running. Allow your vehicle to idle for a few minutes on level ground to achieve this, then switch off the ignition.
Next, raise your vehicle with jacks and make sure it’s secure. You’ll need to work on the underside.
Just as you prepared yourself to get mucky, you’ll need to protect the ground or garage floor as well. Lay down a tarpaulin or large section of cardboard underneath a large catch pan ready to catch the fluid you’re draining.
Important! If you’re not sure where to find the gearbox casing on the underside of your vehicle, check your vehicle’s handbook.
Gradually unbolt and remove the transmission pan
First, loosen and remove two bolts on one side of the pan. Be careful to avoid touching hot fluid or exhaust parts.
Next, gradually loosen the bolts on the other side of the pan. This should let the pan tilt, allowing some of the fluid to drain out. Once the flow has slowed, cautiously remove the bolts entirely and lower the pan away from the vehicle. Then you can deposit any remaining oil into the catch pan.
In some cases, you may need to break the gasket seal. This can be done with a screwdriver or similar tool.
Some vehicles have a drainage hole in the pan to make this part easier. Refer to your manual if you’re not certain.
Clean the gasket surfaces
Check the interior of the pan for any signs of damage. If all is well, use a solvent to clean it out. If not, seek advice from a mechanic.
Replace the transmission filter
Take out the old transmission filter – be careful, as this contains oil as well. The filter should come with an O-ring which should also be removed.
Next, put the new filter into position, ensuring the O-ring is also in place.
Apply a new gasket seal to the transmission pan
The gasket seal helps to avoid gearbox oil leaks, so it’s a vital component. Use oil-soluble grease to attach the new gasket. Don’t use gasket sealer or adhesive, as this can make it harder to remove the pan for future changes and may affect how well the gasket seals.
Bolt the pan back into position
Check your vehicle’s manual, as you may need to use a thread sealer on these bolts. Follow the instructions within and tighten the bolts with your fingers at first.
Once you’re satisfied with the position, you can torque the bolts to your manual’s specification to ensure a tight seal.
Refill the gearbox oil
Lower the car down onto its wheels and fill the transmission with gearbox oil. Always make sure you’ve got the right oil for your vehicle before you start to fill it.
Important! Use the dipstick to check your oil level as you fill – don’t overfill it!
Final checks
Switch on the ignition and allow your vehicle to idle for a minute or two to warm up. Then turn it off again and check underneath your vehicle for any leaks.
If all is well, warm the transmission up to operating temperature like you did earlier. Move your gearstick through all the gears to ensure they’re well coated in the lubricant, then take it out of gear or return it to park.
Last but not least, check the oil level with your dipstick while the vehicle idles.
When to change the gearbox oil
Some vehicles have a monitoring system that alerts you when it’s time to get your gearbox oil changed, but this isn’t always the case. If your vehicle doesn’t do the job for you, how can you tell when it’s time?
Well, firstly, bear in mind that the gear oil should be changed at regular intervals. These are:
- Every 30,000 to 50,000 miles for manual gearboxes
- Every 60,000 to 100,000 miles for automatic transmissions.
You should also have your gearbox oil changed if:
- You’ve just had a gearbox leak repaired
- Your oil has changed colour
- There is physical debris in the oil – for example, dirt or metal shavings from the components.
If all this sounds like more hassle than it’s worth, don’t worry. You can always take your vehicle to a qualified mechanic for all your gearbox needs, helping you to ensure your vehicle gets the best possible maintenance. Whatever you need, we’re happy to help.
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