How to check automatic transmission fluid

This fluid keeps your automatic gearbox healthy by lubricating the key components of the transmission system.

Over time, the fluid can lose its ability to lubricate the transmission effectively. The fluid level can also drop over time due to wear and tear - that's why the ATF should be checked regularly and topped up or replaced as necessary.

In this guide, we provide all you need to know about ATF.

What is automatic transmission fluid?

Automatic transmission fluid, or ATF as it is also known, is a specialised fluid used in a vehicle with an automatic gearbox. It enables smooth gear shifts. It also reduces wear and tear on the internal components of the gearbox.

Normally a dark red or pink fluid, ATF is essential for efficient transmission operation and should be checked regularly to ensure optimal gearbox performance and longevity.

Automatic transmission fluid can inspected by a trusted local garage or by a mobile mechanic. In some cases, you can also check the fluid yourself.

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How to check your automatic transmission fluid level

Depending on the type of automatic car you own, the process for checking the transmission fluid will be carried out digitally or manually.

For example, some automatic vehicles have a sealed transmission system, which means there is no dipstick to check the fluid level.

If the transmission is sealed, the fluid level and its condition will be monitored electronically by the vehicle's computer system. If there is a problem with a sealed automatic transmission system, you will be informed via a dashboard warning light.

If you have an automatic vehicle that has an ATF dipstick, checking the fluid level is a relatively simple task that you can carry out at home with minimal tools, but it must be done correctly and according to the manufacturer’s instructions.

If you are unsure how to check your vehicle's automatic transmission fluid or do not have the confidence to do it yourself, speak with a qualified professional. Checking the fluid incorrectly could result in long term damage to your vehicle. 

Preparation

Before starting to check your automatic transmission fluid levels, it’s important to consult the vehicle owner’s manual.

This will provide you with the dipstick location and include a step-by-step process you will need to follow to check the fluid safely and correctly. 

The owner' manual should also tell you what transmission fluid you will need to use if you need to top it up. 

Remember to wear gloves to protect your hands when checking the fluid level.

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Park in a safe and level space

Make sure that you park the vehicle on a flat surface and engage the parking brake.

In some cases you may be required to keep the engine running in order to check the transmission fluid correctly - consult with the owner's manual to confirm this. 

Locate the automatic transmission fluid dipstick

The transmission fluid dipstick is usually located near the back of the engine bay.

It is likely to be labelled or have a brightly coloured handle (often red or yellow) to distinguish it from the engine oil dipstick. If you are unsure, refer to your vehicle’s manual.

Inspect the dipstick

Pull the dipstick out carefully, wipe it clean with a cloth or paper towel, then reinsert it fully.

You will then need to remove it again and observe the fluid level and condition.

Check the fluid level and condition

The dipstick will have the markings ‘Full’ and ‘Add’ – or something similar – and the fluid should be within the marked range. If it is at or below the minimum, it may need to be topped up.

Examine the fluid’s colour. Healthy ATF is typically dark red or pink in colour.

If it appears much darker in colour, e.g. dark brown, it will need to be checked by a qualified professional. Speak with a mobile mechanic or your local garage.

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Add automatic transmission fluid to your car

If the fluid level is low and you need to top it up, consult with the owner's manual on the process you need to follow to add transmission fluid or speak with a qualified professional.

You may need to use a funnel to add the fluid in small amounts. Be careful not to overfill or spill it on the engine. Remember to wear gloves to protect your hands.

Once you're finished, securely re-insert the dipstick and close the bonnet.

Drive a short distance to check if any engine warning lights appear. If they do, then you may need to take the vehicle to your trusted local garage or speak to a mobile mechanic.