Your car depends on a number of different fluids in order to work properly. You probably know what many of them are: engine oil, coolant, steering fluid, brake fluid, and many others. Every fluid plays an important role in making your car work: some contribute to cooling your engine or various components, others lubricate moving parts, others keep friction from causing irreparable damage to your engine or transmission. However, fluids all have something in common: they do eventually need to be changed.

Each fluid is different in regards to how often it needs to be maintained, or flushed, as well as what can happen if you don't service it. Here are some of the most important fluids in your vehicle, including which ones you need to maintain, change or flush the most.

Engine Oil

There’s no question that the fluid that must be changed the most is engine oil. Engine oil is responsible for lubricating your engine cylinders (the spaces in which your pistons continuously move up and down to generate your power). Because it’s exposed to thousands of explosions every second, your engine oil will very quickly begin to blacken and pick up debris like tiny bits of dust or burned substances. After even just a few thousand miles, oil that went into your engine a beautiful shade of clear copper looks black, dirty, and destroyed. And that’s not a good thing: dirty oil provides extra friction, and extra friction means further wear and tear on your cylinders, pistons, valves, seals, and so much more.

How often you should change your oil depends on the make and model of your vehicle, so consult your owner’s manual for your manufacturer recommended oil change interval. Most vehicles recommend changing your oil between 3,000 and 5,000 miles, but some can go as high as 7,000 or 8,000 between changes.

Coolant/Radiator Fluid

Coolant is the name given to a mixture of antifreeze and water which flows through your radiator and cooling system. This fluid is responsible for removing heat from your engine quickly and effectively. If your engine gets too hot, the metal which it’s built from eventually weakens, which causes cracks, leaks, or eventually total engine failure. To do this, your cooling system runs coolant through your engine, allowing it to absorb heat from the block, which it then carries out to your radiator. Your radiator passes this blistering hot coolant over a series of fins and fans, which use the power of moving air to remove heat from the fluid so it can be cycled back in.

Over time, coolant degrades like any other fluid in your vehicle. As antifreeze ages, it picks up a number of small bits of debris and deposits, all of which cause your coolant to lose its ability to absorb heat. They also cause leaks in coolant hoses and plenty of other issues. Flushing your coolant system out is something we strongly recommend during the lifetime of your vehicle - generally every 30,000 to 50,000 miles.

Power Steering Fluid

If you’ve ever driven a car without power steering, you know how important this fluid is. Without power steering, turning a car is extremely difficult, requiring a large amount of upper body strength and endurance to do so over a longer period of time. Power steering is a hydraulic system, which means it uses a piston pressing on fluid in order to make your wheels turn, and today’s systems have become so precise and stable that they’re pretty much standard in all vehicles built for the United States market these days. However, this does add to your maintenance as you’ll need to flush out your power steering fluid periodically. We recommend about every 50,000 to 75,000 miles, depending on your vehicle and how much you drive.

Flushing your power steering fluid does take some work, and it’s strongly advised you don’t try to do this service on your own unless you have the right tools and experience to know what you’re doing. You also need to make sure you’re using the right power steering fluid for your vehicle. These fluids all react to different pressures in different ways, and using the wrong fluid could cause irreparable damage to your vehicle.

Transmission Fluid

Finally, your transmission fluid also needs to be flushed periodically in order to keep your transmission flowing smoothly. Transmission fluid plays two important roles: lubricating your transmission so each of the finely-fitted components will interact with as little wear as possible, and removing heat from these components caused by friction as they rub together. As your transmission fluid cycles through your vehicle, it accumulates waste, thickens, and forms sludge which can significantly reduce your transmission’s performance, reduce vehicle power, and even contribute to transmission failure.

We recommend replacing your transmission fluid every 75,000 to 100,000 miles, depending on manufacturer recommendations. However, if your vehicle is used for heavy duty applications, such as towing, performance driving, or heavy hours of driving each day (like a corporate vehicle) you may want to have your transmission fluid changed every 50,000 miles or so. If you have any questions, we recommend talking to a certified mechanic to learn more.

About Christian Brothers Automotive

Whether you need an oil change, a fluid flush or other type of maintenance or repair, Christian Brothers Automotive can help! We offer a full range of automotive services from certified technicians as well as a customer-first experience that you won’t find anywhere else.

Schedule a service with your local Christian Brothers Automotive! Give us a call or contact us online to get started.

** Editors note: This blog was originally published in 2014 and revised in 2019 to include new and updated information.