From engine oil and power steering fluid to brake fluid and coolant, your car depends on many different fluids to work properly, and every fluid has a different role. Some contribute to the cooling of your engine and various components in your car, while others lubricate moving parts and prevent friction and possible damage to your engine, transmission, and more.

While every fluid is different and each plays a different role in the health of your car and the safety of yourself and your passengers on the road, all your vehicle's fluids have something in common: they will eventually need to be flushed and replaced.

Are Fluid Flushes Necessary?

Flushing certain fluids out of your car and replacing them with completely new and clean fluid increases longevity and avoids future problems like these:

• Poor acceleration

• Unreliable stopping power

• Unsafe driving conditions

• Difficulty steering

• Damage to engine

• Poor fuel efficiency

• Overheating engine

Each fluid is different regarding how often it needs to be flushed out of your vehicle's system and what can happen if you don't service it.

How Can I Tell if My Car's Fluids Need to Be Flushed?

There are a couple of ways you can know if it’s time for a fluid flush. Your vehicle’s owner’s manual likely details a maintenance guide for recommended fluid flushes based on the mileage of your car. Your local Christian Brothers Automotive technician can take this a step further by inspecting your fluids to see if dirt, debris, and other gunk have built up in fluids due to a lack of regular maintenance.

Fluids That Must be Flushed from Your Vehicle & Replaced

Here are some of the most important fluids in your vehicle, including which ones you need to flush on a regular maintenance schedule:

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).

Since it's exposed to thousands of explosions every minute, your engine oil will very quickly begin to blacken from the combustion process. After just a few thousand miles, the oil that went into your engine as a beautiful shade of clear copper looks black, dirty, and destroyed. And that's not a good thing: dirty oil provides extra friction, which 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's recommended oil change intervals. 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. Don’t wait too long for your oil change though; the damage can be severe.

Coolant & Radiator Fluid

Coolant is the name given to a mixture of antifreeze and water which flows through your radiator, engine, and cooling system, removing large amounts of heat from the engine block and carrying it to your radiator. The radiator then takes the extremely hot coolant over a series of fins and fans that cool the fluid, so it can be cycled back in.

Over time, coolant degrades like any other fluid in your vehicle. As it ages, the ratio of water and coolant changes, increasing the level of water. When this happens, it becomes much more acidic, which makes it more conducive to electrical current. The longer an electrical current runs through the fluid it will cause corrosion of parts, especially those made out of aluminum. And, it’s good to know that many parts on a car these days are made of aluminum, including the engine block of most newer cars. The corrosion of parts is the primary reason to have your coolant flushed regularly.

As the antifreeze ages, it will not only break down but also pick up a number of small bits of debris and deposits, all of which cause your coolant to lose its ability to absorb heat. Without clean and clear coolant your engine would get too hot and cause the metal it's made of to eventually weaken, leading to cracks, leaks, or even total engine failure.

This debris can cause leaks in coolant hoses and plenty of other issues as well. Flushing your coolant system out is something we strongly recommend during the lifetime of your vehicle - generally every 30,000 to 50,000 miles - another detail you can find in your owner’s manual.

Power Steering Fluid

If you've ever driven a car with low or no power steering fluid you know how important this fluid is. Without power steering, turning a car is extremely difficult and near impossible, requiring a large amount of upper body strength and endurance to do so over a longer period of time.

Your power steering system is a type of hydraulic system that uses a piston to press on the fluid in order to make your wheels turn, and, you guessed it, the fluid will need to be flushed and replaced. Luckily, today's systems have become so precise and stable that they're pretty much standard in all vehicles built for the US, making power steering fluid flushing an absolute breeze. We recommend having it flushed 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 that you don't try to do this 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. Power steering fluids all react to different pressures in different ways; using the wrong fluid could cause irreparable damage to your vehicle.

With technological advances, automobile manufacturers have begun making cars with electric power steering systems, eliminating the need for power steering fluid altogether. Your local Christian Brothers auto expert will inspect your vehicle and happily share with you if your newer car has fluid or if it has an electric power steering system.

Transmission Fluid

Finally, your transmission fluid will need to be flushed periodically, because the 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 – all expensive repairs that can be avoided by adding this preventive maintenance to your routine auto care.

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 auto mechanic to learn more.

How Can I Have My Vehicle's Fluids Flushed?

While you may be considering handling your vehicle's fluid maintenance on your own, it's best to leave anything besides topping things off to the professionals. Bring your car to a local automotive shop to have:

• Old fluid removed from the system

• Debris from the fluid reservoir flushed out

• Filter replaced

• Fresh fluid added to the system

Request Your Fluid Flush from Your Local Auto Mechanic at Christian Brothers Automotive

Whether you need an oil change, a fluid flush, or another type of maintenance or repair, Christian Brothers Automotive can help! We offer a full range of automotive services from knowledgeable and expert technicians as well as an industry-leading, customer-first experience that you won't find anywhere else. Let’s not forget our surprising lobby, where you’ll often find complimentary coffee and snacks.

Schedule a service with your local Christian Brothers Automotive – use our store locator and reach out today to get started!

This blog was written in June, 2014, but updated in August, 2023, to reflect current industry standards and best practices.