7 Essential Car Fluids and What to Know about Each in your vehicle:

Motor Oil

Motor oil is the most important fluid in every car with an internal combustion engine. Oil lubricates the moving parts in a car engine’s crankcase, preventing the high heat and friction that results during engine operation from destroying the pistons, valves and other components. Without oil, a running engine will seize up in a short time, making the engine virtually unusable.

Brake Fluid

Brake fluid is by far the most important car fluid in terms of passenger safety. A car’s brake line system is a fully-sealed network that uses hydraulic pressure to control the car’s ability to stop. When a driver presses down on the brake pedal, the brake fluid compresses, transferring the hydraulic force to the pads and shoes that cause the friction necessary to stop the vehicle. If brake fluid leaks or if too much air gets into the brake line, a car’s ability to stop will be compromised.


Coolant is most commonly a 50/50 combination of water and specialized radiator coolant. In colder climates this ratio will lean more heavily towards coolant. Coolant is a heat transfer fluid. It cycles around a running engine, collecting heat as it does and returns it to the radiator. From there, it is transferred to the air. Without proper coolant levels, a car will quickly overheat and be inoperable.

Transmission Fluid

Transmission fluid is reddish in hue and usually does not have to be checked by a car owner. Similar to motor oil, transmission fluid cools and lubricates the inner parts of the transmission, ensuring that the engagement of the car’s system of gears works without a hitch.

Power Steering Fluid

This fluid, pressurized by a small hydraulic pump powered by the engine, helps to make turning a car easier. When working at proper levels, power steering fluid increases the ability of the steering mechanism to direct the tires.

Battery Fluid

Cars with maintenance-free batteries don’t require checking the battery fluid. Other car batteries, however, must have their individual cells refilled from time to time. Fill up each cell to the bottom of the fill line with distilled water.

Windshield Wiper Fluid

While this is a non-essential fluid in terms of a car’s ability to operate and stop, windshield wiper fluid provides a fast means of clearing the windshield of dust, bug residue and other particles while driving. The fluid is basically liquid soap and is very easy to maintain.

Simply by taking the time to bring your vehicle in to ADVANCED AUTO DIAGNOSTICS periodically we will check these fluids, to ensure your car enjoys a healthy, safe level of operation. While some are more important than others, they all contribute to a sound automobile.