29 April 2021
Wet Works: The truth about the fluids and coolants in your car

Besides petrol, these other fluids and coolants are essential to keep your car running reliably.

If you think about it, a car is a collection of thousands of metal parts that are kept off the ground by four round rubber tyres. In order for a car to move, all these parts, especially those of the engine and gearbox have to move in tandem. The spark plug ignites the fuel in the cylinder, which pushes down the piston. This in turn causes other parts to move until eventually, they turn the wheels.

Engine oil

When one metal part comes into contact with another, wear and tear occurs. To minimise this, a thin film of engine oil get in between the surfaces. In some areas of the engine, this film of oil is thinner than a strand of human hair.

Gearbox fluids

Likewise, the gearbox is another complex bit of machinery that transmits the engines’ power to the wheels. Instead of engine oil, the gearbox uses a special type of lubricant to keep the parts from destroying each other. Known as the transmission fluid, it facilitates smooth gear shifts.

Metal parts rubbing against each other can be quickly damaged without the right lubrication to protect them.

Modern self-shifting gearboxes are highly sensitive pieces of technology. To the point in fact, that most gearboxes are designed to work with a specific grade of transmission fluid. When it comes to gearboxes, this is one fluid that you should not switch to another brand or grade. Replace the fluid with only the exact type specified by the vehicle’s manufacturer.

There are also different types of transmission fluids for each type of gearbox.

  • Automatic gearbox: Automatic Transmission fluid (ATF)
  • Continuous Variable Transmission (CVT) gearbox: CVT fluid
  • Automated dual-clutch or multi-clutch gearbox: Dual-clutch transmission (DCT) or Multi-clutch transmission (MCT) fluid
  • Manual gearbox: Gearbox oil

Gearbox fluids last longer than engine oils and are usually recommended to be replaced every 50,000 to 80,000km. Ignoring these intervals can lead to gearbox failure, and replacements are costly.

It is highly recommended to use manufacturers’ recommended transmission fluids for your car’s gearbox.

If you are not sure what type of gearbox your car has or if you need it serviced at a reputable workshop, AutoApp can help.

Brake fluid

When the driver presses the brake pedal, the brake pump gets a signal to push fluid to the brake calliper with enough pressure to stop or slow the brake disc inside the wheel. This is known as brake pressure. The stronger the brake pressure, the stronger the stopping power, and this power is transmitted by the fluid.

Brake fluid tend to absorb moisture, which reduces its effectiveness. Replacing every year or so would be a good idea.

The nature of brake fluid however, is that it is hyrgroscopic. This means that it tends to absorb moisture from it’s environment, like a sponge. If the brake fluid absorbs too much moisture, and its water content exceeds 3%, this can compromise its ability to transmit brake pressure effectively. The result is usually described as “spongy” brakes, and the driver needs to push the brake pedal further than usual to stop or slow the car.

In a humid climate like Singapore’s, brake fluid should be replaced at least once a year.


Engines naturally generate heat when they operate. This heat however, needs to be managed as excessive amounts can lead to catastrophic damage or even fires! Just about every modern car engine is cooled by a liquid coolant that circulates around the engine block. The coolant then goes through a radiator to be cooled by the air moving through the engine bay as the car travels, or air blown by an electric fan if the car is stationary. In other words, the coolant carries heat away from the engine.

The pink coolant in a white expansion tank makes it easy to check the level without needing to open the cap.

Because of the extreme heat the coolant is subjected to, some evaporation might occur, or there might be a leak in the system, however small. The coolant level in most engines can easily be checked by observing the fluid reservoir tank that is usually translucent. The coolant is usually pink or bright green, which makes makes it easy to identify.

If you’re still unsure of what to check for, just download the AutoApp smartphone app and book an appointment. A Service Ambassador will arrive at your doorstep to get your car checked for these fluids and anything else your car might need.