Car Fluids and Their Functions

From keeping your engine moving to ensuring your windshield is clear, cars have numerous fluids for keeping it on the go. We’ve put together a list of the key car fluids you need to know and how they work to run your vehicle smoothly.

Transmission Fluid

Each time you switch gears, for example from drive to park, your transmission will send the right amount of power to your wheels. As a crucial element of your vehicle, your transmission needs to be cared for with proper transmission fluid. This car fluid provides the following benefits.

    • Regulates the temperature 
      • Enables smooth gear changes
        • Protects and ensures durability

        Synthetic vs Traditional 

        Once you’ve reached the 50,000-mile mark, it’s time to top up your transmission fluid. When you bring in your vehicle, a mechanic will ask you whether you prefer synthetic or traditional fluid. The major difference is that synthetic is less likely to break down or oxidize in high temperatures. However, the 2 options have different price points and are both viable.

        Brake Fluid

        As the main safety feature of your car, brakes use hydraulic fluid to transfer your force into pressure that will stop the vehicle. When the fluid gets too low, air bubbles will enter your brake line leading to problematic braking.

        Signs Your Brake Fluid is Low

        • Braking problems
        • Illuminated brake light in dashboard
        • Burning scent

        If you see that your brake fluid is at or above the minimum line, you do not need to add more. Referring to an owner’s manual is the best way to find the recommended time frame for refilling your specific vehicle. 

        Engine Oil

        Motor oil, also known as engine oil, is used to keep the moving parts in your engine functioning at optimal conditions. The major functions of engine oil are lubrication, removal of contaminants, temperature regulation, and corrosion prevention. All of these elements are key to your engine running properly.

        Types of Engine Oil

        • Fully synthetic – fewer impurities, highest quality, and cost
        • Semi-synthetic – still high quality but lower cost than fully synthetic 
        • High mileage – specific oil for vehicles that have over 75k miles
        • Conventional – industry-standard, optimal for most vehicles

        Depending on your vehicle’s make and model, you should have your oil changed every 3,000 to 5,000 miles. The more you drive, the more the oil in your vehicle will break down and coagulate. Eventually, this will clog key components and damage the engine as a whole. Regularly changing your oil should be a priority for vehicle maintenance. 

        an auto technician changing the oil on a car that is elevated

        Power Steering Fluid

        Every time you move your steering wheel, hydraulic fluid is used to communicate the movement to the power steering system. This fluid not only assists with turning but also provides lubrication to all of the elements in the power steering system. 

        Signs It’s Time For Replacement 

        • Difficulty steering, wheel resistant to turning
        • Fluid appears dark or has a burnt odor
        • Debris in the fluid

        Typically, vehicles need a power steering fluid flush every 40,000-80,000 miles. However, your optimal routine depends heavily on the type of vehicle.


        While coolant may not need frequent replacement like engine oil, it plays just as crucial of a role in your vehicle. Car engines create an immense amount of heat that would make them dangerous if there wasn’t a way to regulate the temperature. Coolant does just this. As it passes through the engine, it picks up any excess heat, then moves to the radiator where it is cooled before returning to the engine. 

        When Should I Refill My Coolant?

        On average, vehicles are recommended to have their coolant flushed every 30,000 miles or 2 years, whichever comes first.

        If your dashboard indicates that your engine is cold, open up your hood and find the reservoir. It should be translucent, with a minimum fill line on the side. If your coolant is above that line, you are in the clear.

        Windshield Washer Fluid

        The worst feeling is being on the highway with a dirty windshield and no fluid coming out to clean it. Luckily, windshield wiper fluid is the easiest to maintain on your own and can be bought at both grocery and auto stores. Below is a simple step-by-step process for refilling your windshield wiper fluid.

        1. Open your hood and find the washer fluid reservoir—it usually has a windshield/water symbol on the cap
        2. Remove the cap and check the fluid level
        3. Using a funnel, carefully pour in new liquid until it almost reaches the top

        Get Your Car Fluids Checked At City Auto Repair in Gainesville, FL

        It’s important to get your fluid levels checked regularly through regular maintenance. City Auto Repair is a local mechanic here to not only keep your car on the road but to make sure it’s running at its best. We are a full-service auto repair shop and can handle all of your car’s needs. 

        Reach out to us today to schedule an appointment.