A mechanic recently took to TikTok to share a piece of advice: Don’t ever refill a vehicle’s brake fluid.
In the video, which has garnered over 102,900 views at the time of writing, auto shop owner and mechanic William Chang (@concept3performance) demonstrated how he typically does a brake inspection.
Why vehicles don’t require more brake fluid
“Random tip of the day for you guys.” Chang begins. “How to do a simple brake inspection.”
Using a Honda Civic as an example, he explains the first thing he does is check the brake reservoir to see how much fluid is inside.
“My first thing when I do a brake inspection is look at the brake reservoir and see how much fluid is in it between the max line to the minimum line,” he says. He points out that the reservoir, in this case, is “a little bit under the max line.”
Then comes the heart of his advice: Never top off your brake fluid just because it’s low.
“Brake fluid doesn’t dissipate,” Chang explains. “Brake fluid is low because it went into the pistons because your brake pads are low.”
According to him, the fluid level serves as a kind of gauge for the life of your brake pads. If the fluid level is near the minimum mark, it’s time to check if your brake pads are wearing out.
He adds, “If your minimal gauge is on the minimal side, somewhere in the car, front axle or rear axle, you’re out of brake pads.”
What else is important to know about your brakes?
For those unable to check the fluid, Chang suggests inspecting the brake pads themselves.
“If you can’t see the [depth] of the pad, what I do is I look right here between the brake pad itself and the edge of the clip,” the mechanic explains while pointing at the part. “You see how deep it is?”
Chang then further explains why topping off the fluid is a bad idea.
“When we actually work on the car, we push the brake pistons out back. Guess what happens to the fluid that was in the piston that the reservoir took? It goes back up there.”
This means the fluid will overflow, causing unnecessary mess and complications for the mechanic.
@concept3performance Random brake tip of the day! – – – #mazdaspeed #nation #car #jdmnation #honda #rotor #japan #club #rotarypower #nsx #stancenation #rb #gt #nismo #miata #jdmdaily #subaru #wankel #silvia #a #racing #mx #carsofinstagram #mk #supramk ♬ original sound – Concept 3 Performance
Other common causes for low brake fluid
According to Sun Service Auto, low brake fluid levels in a car are typically caused by three common issues.
The first is a leak in the system, which can occur anywhere from the master cylinder to the caliper. Such leaks can quickly deplete the amount of brake fluid available.
The second, as the mechanic in the TikTok video explained, involves worn brake pads. “When pads are worn down, the caliper piston is forced to travel farther to the brake pads, away from the housing,” the auto shop notes. “This requires more brake fluid to travel further down, which may become depleted over time.”
The third most frequent culprit is damaged brake lines. Over time, brake systems can wear out, and steel components may rust, leading to compromised functionality.
The site emphasizes the importance of addressing low brake fluid immediately. Ignoring it could lead to a total brake system failure, posing a significant safety risk.
Viewers react
In the comments section, not everyone agreed with the mechanic. Others offered additional tips and shared their stories about brake fluid issues.
“Don’t agree. Top it. If you want to check caliper, check caliper,” advised one viewer. “If you are on the run and start leaking, having fluid on max can be the difference on a tow or get into the garage or home safe.”
“I agree about not topping off, but I always crack the bleeder when compressing the pistons,” another wrote. “Don’t want dirty fluid going back into the res.”
“My first truck at 16, I topped off the fluid and proceeded to do a brake job,” a third shared. “Needless to say I had a mess. Lesson learned.”
The Daily Dot has reached out to William Chang via email and Instagram direct message.
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