Checking Your Cars Fluids

AutoTrader NZ
Published 3 September 2020

Like people, cars need good fluids to keep them going and hydrated. Engine oil is obviously the main one, as it’s so key we have a separate guide to checking your engine oil. But there are also many other fluids that help keep your car running smoothly. Below is a guide on how to check these fluids and what to look for. 


1. Coolant or antifreeze does many things and is not the same as just adding water to your radiator. Your coolant can come in a range of colours, green being the most common but it can also be red, blue, orange, pink and purple. Having just water will cause a brown rusty colour and should be replaced with a  coolant concentrate mix As soon as possible. 

Antifreeze or coolant concentration mix has properties that stop your engine rusting as well as being safe for the plastic hoses. But more importantly coolant cannot freeze or overheat as easily. Your coolant reservoir can easily be mistaken for your washer fluid and every manufacturer has a different looking coolant reservoir, so make sure you have the right one by checking your owner’s manual. Only open the reservoir cap when the engine is cold, this is very important as it is pressurised and can cause injury.

2. Brake fluid is often one of the forgotten fluids as it only needs replacing every few years usually. Brake fluid can degrade over time as it is hygroscopic and attracts water. If your brake fluid absorbs too much water the fluid can boil and lead to brake failure, so it is a very important fluid to check.

To test your brake fluid you can use either brake fluid test strips or an electronic brake fluid tester. A noticeable sign your brake fluid is old and needs replacing is if it is a dark colour, brake fluid can come in a range of colours mainly a slight yellow tint is common. Below is where you will find your brake fluid reservoir. Make sure you use the correct dot fluid, this can be found on your brake fluid reservoir cap or in your owner’s manual.


3. Transmission fluid is extremely important for keeping your gear changes smooth both manual and automatic use transmission fluid. 4WD’s also use transmission fluid in the differential cases. 

Transmission fluid is also often a forgotten fluid but is vital to check every so often to save you from a very large bill that can easily be in the thousands if your transmission needs replacing. 

Each car will have a different way of checking transmission fluid, some use a dipstick, which can usually be found tucked away next to the engine and measures if your fluid is high or low. Newer vehicles do not have a dipstick so ask your mechanic if your transmission fluid needs to be checked and at what intervals. If you are not sure, check your owners manual and make sure you stick to the required servicing intervals for changing your transmission fluid.