Tech Talk with Master Power Brakes

How to Prep Your Brake Fluid for Spring Driving

Posted by Master Power Brakes Team on Mar 29, 2021 4:10:49 PM

classic car

You can just feel it, can’t you? Warmer weather is right around the corner.

Now’s the time to start working on your classic car checklist so that your ride will be ready for spring.

Here’s why you should focus on preparing your brake fluid for the upcoming change in season.

How Do I Prep My Brake Fluid for Spring?

It’s a good idea to change your brake fluid every spring. Here’s why.

As a vehicle sits for a long time over the winter months, condensation forms within the master brake cylinder as well as the braking system. This creates droplets of water, which most brake fluids absorb. 

However, that moisture alters the characteristics of the brake fluid’s functionality. The absorption of water changes the boiling point and the viscosity of the brake fluid. Moisture affects how the brake fluid compresses within the system.

When it comes to different types of brake fluids, DOT 3 and DOT 4 are hygroscopic, which means they absorb water. DOT 5 is silicone-based, so it doesn’t absorb water. The problem with DOT 5 is that moisture will puddle instead of seeping into the brake fluid and cause rust within the braking system.  

Why Should Classic Car Owners Change the Brake Fluid?

Changing the brake fluid every spring is particularly advisable for classic car owners for a few reasons. 

Hot rods tend to be stored during the winter months, while modern cars stay on the road. If a vehicle is not being driven regularly and generating heat, the condensation problem will creep up sooner.

You’ve probably heard the saying, “They don’t make ‘em like they used to.” It’s true. Classic cars tend to have cast iron components, which are more prone to rust. However, modern car parts are made of aluminum, which is corrosion-resistant.

So you can see why a classic car with original parts that’s been sitting in the garage for three months may experience brake fluid issues faster than a normal vehicle. But even if you continuously drive your hot rod in the winter or get around town in a newer car, changing the brake fluid in spring is still a great, proactive way to maintain your vehicle.

What Master Power Brakes Products Can Help With This?

When you do change the brake fluid in your classic car, you’ll have to bleed out the braking system. Our syringe bleeder kit allows you to fill the syringe, inject fluid into each port, and you’re done. 

We also sell a high-quality, hygroscopic brake fluid. Pentosin Super DOT 4 synthetic fluid offers a chemical makeup that’s more resistant to moisture and contains the proper rust inhibitors you need for your classic car.

What Else Should I Do to Prep My Car for Spring?

There are other things you can do to get your classic car ready for spring driving. Here’s a list of areas to check within the braking system, as well as the rest of your vehicle.

Wheel Bearings

If your wheel bearings are worn, replace them as necessary. If the wear seems minimal, remove them for cleaning and repack with a quality wheel-bearing grease.

Wheel Calipers & Cylinders

Caliper and cylinder seals can become dry and stuck in a vehicle you haven’t driven in some time.

Master Cylinder

Be sure the rubber seals inside your master cylinder haven’t dried out. Drying can cause sticking, leaks, and poor performance—just like with the seals of your wheel calipers and cylinders.

Vacuum Hose

Make sure your existing hose isn’t dry or cracked. This can easily happen because of its exposure to high temperatures inside the vehicle. 

Brake Pedal Pressure

Once the car is running, press the brake pedal and compare it to what it felt like when parked. If it feels different, you should investigate.

Parking Brake

Moving pieces inside the cables can become seized, so make sure they are free and unrestricted.

Wipers, Tires, Bulbs, & Fluids

Spring is a great time to check your wipers, tires, bulbs, and other fluids to keep your car safe and performing at its peak.


Do a check to make sure your battery life is still at full strength.


Last but not least, give the body and undercarriage a good wash, start the engine and let it run for a bit, then you’ll be ready to hit the road!

front of a classic

How to Prep Your Brake Fluid for Spring Driving

Now you know why you need to change the brake fluid in your classic car before you head out this spring.

When a hot rod sits all winter, moisture can seep into the brake fluid and affect its performance. You need to ensure your braking system is in top condition before you roll out of the garage.

If you have more questions about caring for your classic car, Master Power Brakes has the answers. Talk to our experts today!

Topics: Brake Maintenance, Parts

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