Bronco Fluids: When & Why to Flush

Keeping parts functioning properly. Ensuring the engine runs smoothly. Preventing wear and tear. These are just some of the things you can do for your Bronco or Sport with proper maintenance. This is especially true when it comes to fluids. There are many fluids that are vital for the proper operation and longevity of your Bronco, including engine oil, transmission fluid, coolant, brake fluid, and differential fluid.

I once again connected with Kyle Stone, our fellow Bronco Nation member and Senior Master Technician through Ford, to get some insight about the different fluids. He recaps below why it is important to stay on top of them, what they do, and when they should be replaced.

“The normal maintenance schedule from Ford is still definitely a good guideline to go by,” says Kyle. “I usually try to change out my fluids more often than the standard maintenance schedule (100,000 miles for most fluids), so we can just chalk that up to being a personal preference of mine. I prefer to change out all fluids every 50,000 to 60,000 miles, and change the oil every 5,000.”

ENGINE OIL
Let’s start with the most commonly changed automotive fluid. Which, unfortunately, can also sometimes be the most neglected. Engine oil helps keep your engine lubricated and is imperative to keeping your vehicle operating properly. Over time, oil will break down and lose its ability to lubricate the engine, and will eventually turn into sludge if left alone for too long. This is especially true on the 6th Gen Broncos, which all have turbocharged Eco-Boost engines. Turbochargers can be very hard on oil, so it’s very important to routinely change engine oil.

How often should I change my engine oil?
I routinely change my oil every 5,000 miles, no matter what. I like to keep a routine, and I like to live with the mentality of "Oil is cheap, engines are not." The 6th Gen Bronco comes with an Intelligent Oil Life Minder system. It tracks how often your vehicle idles, temperatures, and miles driven and can give you a good baseline for changing the oil if your Bronco is a regular daily driver. If you off-road frequently, drive in generally harsh conditions, or drive at high speed or high accelerations, you should change it more often.

BRAKE FLUID
Brake fluid is an often-overlooked fluid on most vehicles, which is unfortunate, as it can pose danger later in the life of any vehicle. Brake fluid absorbs moisture over time, and with that, can cause corrosion in the brake system, or even worse, an overheating braking system — which will cause the brakes to be less effective or possibly not work at all.

How often should I change my brake fluid?
Changing the fluid out every 2 to 3 years is ideal, or my normal rule of thumb for the average driver is to perform a flush anytime you change out your brake pads or rotors.

• Changing it regularly can help prevent brake performance loss and prevent corrosion from forming inside the brake system, which can cause damage to brake lines, seals, hoses, calipers, and master cylinder.
• If you often do a lot of high-speed driving, live in a very humid climate, or routinely get your brakes hot (from towing, braking down inclines, hard braking, etc.), I recommend every year to year and half just to be safe. (More frequent changes means you'll be less likely to need calipers due to sticking pistons or broken bleeder screws.
• TIP: Brake fluid should be a clear, almost colorless to a slightly yellow/amber color. This is the easiest way to tell if brake fluid is getting old and needs to be changed out. There are tools that can be purchased online and in most auto parts stores that can measure/test the amount of water that is in the brake fluid, and these can be found quite inexpensively.

DIFFERENTIAL/AXLE FLUID
Differential/axle fluid is essential to keeping the bearings and gears in the differentials both cool and lubricated. If not properly lubricated, the bearings and gears can become damaged, especially if the fluid gets too hot. Like any other automotive fluid or oil, the differential fluid will break down over time and lose some of its lubricating ability. A flush removes debris and old fluid, maintaining optimal performance.

• For Bronco Sport owners, this applies to the rear differential only
• For full-size 6th Gen Broncos and OG Bronco owners, this applies to front and rear differentials

How often should I change my differential fluid?
Every 100,000 miles is a good guideline to follow for a daily driver or occasional off-roader. However, If you do a lot of off-roading, use the front or rear lockers often, or routinely have your Bronco partially submerged in water — I would change it out every 50,000 to 60,000 miles. Or at the very least, have it checked frequently to make sure no water has gotten into the axles.

AUTOMATIC TRANSMISSION FLUID
Transmission fluid in an automatic transmission not only keeps all the gears and bearings lubricated, it's also the lifeblood of the transmission. An automatic transmission uses the fluid under pressure to apply and release clutches that change the gear the transmission is in. This ensures smoother gear shifting and ultimately helps prevent damage to the transmission. Over time, like all oils and automotive fluid, the transmission fluid can become burnt, contaminated, and worn out.

How often should I change my automatic transmission fluid?
A good rule of thumb is between 80,000 and 100,000 miles. However, if you off-road with a lot of hills/mountain climbing, sand running, or if you tow often — changing it a bit more frequently, around 50,000 to 60,000 miles, would be recommended.

One caveat to automatic transmission fluid: If you wait too long to change it, say around the 125,000 to 150,000 mile mark, I would highly advise against changing the fluid. Over time, some of the friction material from the clutches breaks down and becomes suspended in the fluid, and if you change out the fluid after this has occurred, you can actually create transmission issues such as slipping or poor shifting.

MANUAL TRANSMISSION FLUID
Just like the differential/axle fluid, manual transmission fluid is there to ensure all the bearings and gears inside the transmission are lubricated and move freely.

How often should I change my manual transmission fluid?
The same rule of thumb applies as most fluids: 100,000 miles is good practice for a daily driver. If you're an avid off-roader, drive hard, or tow, I would recommend changing the fluid every 60,000 to 70,000 miles just to prevent excess wear or fluid breakdown.

COOLANT
Engine coolant is crucial to any liquid-cooled engine (all Broncos are liquid cooled). The amount of heat that an internal combustion engine can create is immense, and that heat needs to be moved away from the engine, or severe damage to the cylinder head(s) or a blockage can occur due to overheating and warping. Coolant flushes remove debris and corrosion from the cooling system, helping to prevent that overheating while protecting your engine.

How often should I change my coolant?
Ford recommends changing the coolant at 200,000 miles on the 6th Gen full-size Bronco. That is fine for the daily driver/commuter, but not as good for an avid off-roader or someone who tows. The extra work the vehicle is doing in these scenarios can generate more heat that has to be dissipated faster and that can expedite fluid breaking down.

Over time, coolant will lose it's cold weather protection (needed to keep coolant from freezing) and can cause corrosion in the engine block and cooling system . This can block radiators, thermostats, and heater cores causing costly repairs or damage. If you work your Bronco a bit harder than as just a daily commuter, I recommend changing the coolant every 80,000 to 100,000 miles to keep the coolant free from corrosion build up, and to prevent the engine from freezing.

POWER STEERING FLUID
Power steering fluid (only applicable to pre-6th generation Broncos), keeps the steering gear lubricated, but is also used by a fluid pump to pressurize the fluid to give you the assist that power steering generates. Having this fluid flushed regularly will ensure the system continues to function smoothly

How often should I change my power steering fluid?
If the fluid looks black, or smells burnt, change it out. A good rule of thumb is every 100,000 miles but, as with all fluids — if you're an off-roader, or drive through tough terrain where the steering can be difficult, I would recommend every 50,000 miles.

Whether you decide to/are able to make these fluid changes on your own or opt to take your vehicle in for service at your local dealer — staying on top of the fluids is essential for the longevity of your Bronco. For those changes you’re able to make at home, Kyle advises: “Be sure to check your owner’s manual or service guide to be sure you use the right fluid, using the wrong fluid can cause excess wear and damage.”

“Personally, for my own vehicles, I change my oil every 5,000 miles, and I try to change out all of my fluids, as well as my spark plugs, every 50,000 miles,” he concludes. “As long as you stay routine on your maintenance and take care of your Bronco…your Bronco will take care of you!”

Have any maintenance tips or tricks of your own to share? Have a specific maintenance topic you’d like covered? Let us know below!