Most car owners know the importance of regular oil changes, but your vehicle relies on a whole team of specialized fluids to run smoothly and safely. Beyond the engine oil, there are several other critical fluids working behind the scenes. Forgetting about them can lead to poor performance, costly damage, and even safety hazards. Don't worry, you don’t need to be a master mechanic to keep track of them. This guide is here to empower you. We'll introduce you to these unsung heroes of your car's health, show you what they do, and explain how you can easily check them, giving you the confidence to take control of your vehicle's maintenance.

Beyond the Oil Change: Why Other Fluids Matter

Your car is a complex machine with many moving parts that generate heat and friction. A variety of fluids are essential for lubricating, cooling, cleaning, and providing the hydraulic pressure needed for key systems to operate. Engine oil gets all the attention because it requires frequent changes, but other fluids are just as vital to your car’s long-term health.

Neglecting these fluids can have serious consequences. Low brake fluid can compromise your ability to stop safely. Old transmission fluid can lead to jerky shifting and expensive gearbox repairs. Ignoring your coolant can cause your engine to overheat, resulting in catastrophic damage.

Learning to check these fluids is one of the most empowering things you can do as a car owner. It helps you catch small problems before they become big, expensive ones. Taking just a few minutes each month for a quick under-the-hood inspection puts you in control, saving you money and ensuring your car remains reliable and safe for every drive. We’ve got you covered with everything you need to know.

The Unsung Heroes: Four Fluids to Check Now

Let's dive into the four essential fluids that often get overlooked. We'll explain their purpose, how to check their levels, and what to look for. Before you start, make sure your car is parked on a level surface. For some checks, the engine should be cool, while for others, it needs to be warm. Always check your owner's manual for specific instructions for your vehicle.

1. Brake Fluid

What it does: Brake fluid is the critical hydraulic fluid that transfers the force from your foot on the brake pedal to the brakes at your wheels. When you press the pedal, this fluid creates immense pressure that clamps the brake pads onto the rotors, slowing your car down. Without proper brake fluid, your braking system simply wouldn't work.

Why it's forgotten: Brake fluid is in a sealed system, so it doesn't get "used up" like oil. As a result, many people never think to check it. However, the fluid is hygroscopic, meaning it absorbs moisture from the air over time. This water contamination can lower the fluid's boiling point, leading to a spongy brake pedal and reduced stopping power. It can also cause internal corrosion of brake components.

How to check it:

  1. Locate the Reservoir: The brake fluid reservoir is a small, semi-transparent plastic container, usually located at the back of the engine bay on the driver's side. The cap will often have a symbol of a circle with parentheses around it.
  2. Check the Level: The side of the reservoir has "MIN" and "MAX" lines. The fluid level should be between these two marks. A dropping fluid level can indicate a leak in the brake system or simply that your brake pads are wearing down, which is normal. A service technician should check for leaks if the level drops suddenly.
  3. Inspect the Color: New brake fluid is typically clear or has a slight amber tint. Over time, as it absorbs moisture and contaminants, it will darken to a brown or even black color. Dark, murky fluid is a sign that it needs to be flushed and replaced. Most manufacturers recommend changing brake fluid every two to three years.

2. Transmission Fluid

What it does: Transmission fluid is a multi-tasking powerhouse. It lubricates the moving parts inside your transmission, cools the unit to prevent overheating, and provides the hydraulic pressure needed for smooth gear shifts in an automatic transmission. In a manual transmission, it serves primarily as a lubricant. Healthy fluid ensures your car shifts gears effortlessly.

Why it's forgotten: Many modern cars are equipped with "lifetime" transmission fluid, leading owners to believe it never needs attention. However, "lifetime" is often just the expected life of the warranty period. Extreme heat, heavy towing, and stop-and-go driving can degrade the fluid over time, leading to poor shifting and potentially irreversible transmission damage.

How to check it (for automatic transmissions):

  1. Warm Up the Engine: Unlike most fluids, transmission fluid needs to be checked when the engine is warm and running. Drive the car for about 15 minutes to bring it to normal operating temperature.
  2. Park and Find the Dipstick: Park on a level surface, engage the parking brake, and leave the engine running in Park or Neutral (check your owner's manual). The transmission fluid dipstick is often located toward the back of the engine. It usually has a red or brightly colored handle.
  3. Check the Level and Condition: Pull the dipstick out, wipe it clean with a lint-free cloth, reinsert it fully, and then pull it out again. Check the fluid level against the "HOT" markings. The fluid should be a bright, translucent red. If it looks brownish, black, or smells burnt, it is a clear sign that the fluid is old and needs to be changed.

3. Power Steering Fluid

What it does: This fluid makes turning your steering wheel a breeze. In vehicles with a hydraulic power steering system, this fluid transmits pressure to help you steer the wheels with minimal effort. Low or old fluid can make steering feel heavy and difficult, especially at low speeds. Note that many newer cars have electric power steering and do not use this fluid.

Why it's forgotten: Similar to brake fluid, power steering is a closed system, so it isn't consumed. Leaks are the primary reason for a low fluid level. Many drivers don’t think about it until they hear a whining noise when turning or feel stiffness in the steering wheel.

How to check it:

  1. Find the Reservoir: The power steering reservoir is another plastic container in the engine bay, often with a cap that has a steering wheel icon on it.
  2. Check the Dipstick: Some reservoirs have a small dipstick attached to the cap, while others have "MIN" and "MAX" lines on the side. Some dipsticks have markings for both "HOT" and "COLD" levels, so check your owner's manual to see whether the engine should be on or off.
  3. Inspect the Fluid: The fluid level should be within the correct range. The fluid itself should be clear red or light brown. If it appears dark and foamy, it may have air in the system or be contaminated, and it should be inspected by a professional.

4. Coolant (Antifreeze)

What it does: Engine coolant, or antifreeze, is your engine's temperature regulator. It circulates through the engine and radiator to absorb excess heat and prevent the engine from overheating. In the winter, it prevents the water in your cooling system from freezing, expanding, and cracking the engine block. It's absolutely essential for year-round engine protection.

Why it's forgotten: Many people only think about coolant when their car is overheating on the side of the road. Regular checks can prevent this emergency situation. Over time, coolant loses its anti-corrosive properties, which can lead to rust and clogs in the radiator.

How to check it:

  1. Wait for the Engine to Cool: NEVER open the radiator cap on a hot engine. The system is under extreme pressure, and you can be severely burned by scalding steam and fluid. Always wait until the engine is completely cool to the touch.
  2. Locate the Coolant Reservoir: Find the large, translucent plastic container known as the coolant overflow tank. It will have "MIN" and "MAX" or "COLD" and "HOT" fill lines on the side.
  3. Check the Level and Color: The coolant level should be between the fill lines. Coolant comes in various colors (green, orange, pink, or blue), so the color itself isn't a sign of a problem unless it looks rusty, brown, or has debris floating in it. Murky coolant indicates it's old and needs to be flushed and replaced.