Sparesbox Blog

When Should You Replace Your Transmission Fluid?

By Linda Quan

Mon May 25 2020

You’ll find hundreds of articles on the internet that tell you when to change your transmission fluid, how to change your transmission fluid and even some that tell you to avoid touching your transmission at all costs, but all that conflicting information can get confusing. It’s time we get back to the basics with a crash course on transmission fluid!

What is transmission fluid?

Transmission fluid is a lubricant that is made for lubricating the transmission system, a.k.a. the gearbox, of your car. Automatic transmissions are much more complicated than manual transmissions, so their transmission fluids play a bigger role than just lubricating.


How does transmission fluid work?

Automatic transmission fluids (ATFs) are not just lubricants, they also act as coolants that prevent overheating of the transmission system. Because they are exposed to extreme heat, ATFs will degrade over time. Although the transmission fluid doesn’t ‘disappear’, so to speak, its hydraulic properties will weaken as you drive so ATFs need to be replaced more often.

Manual transmission fluids (MTFs) also degrade over time due to the presence of contaminants, rather than from heat. As you use your vehicle, the synchronisers, bearings and gears wear out and leave small its of metal in the transmission fluid, reducing its lubricating properties.


So… when should you replace your transmission fluid?

Of course, the first thing you should do is consult your owner’s manual for when to replace your transmission fluid. For ATFs, the general rule is to replace it every 50,000–100,000 km (though you should probably replace it before you hit 100,000 km). For MTFs, the guideline is every 50,000–90,000 km. However, this depends on what your vehicle uses as a manual transmission fluid – e.g. regular engine oil, hypoid gear oil, etc.


If it’s time to change your transmission fluid, why not take a look at our huge range of Transmission Fluids? Our fitment tool helps you pinpoint the exact type of transmission fluid for your car – simply input your make and model and we’ll do the hard work for you. At Sparesbox, you can find all of your favourite brands such as Castrol, Valvoline, Penrite, Nulon, Liqui-Moly and more!