Classic Car Brake Fluid

When working on a brake system, you're gonna find you need to make some decisions regarding even things like type of brake fluid. The most common for older classic cars is a type 3. This is a glycol ether based fluid. It's non-compressible. Both the DOT 3 and the DOT 4 are glycol ether formulas.

That means they'll also absorb moisture. That is why it's important to change your brake fluid every year. A lot of guys will neglect the brake system. What this does is the moisture in the air eventually it gets saturated into the fluid and causes corrosion in the lines and also in your wheel cylinders and calipers. So you wanna make a good practice out of flushing your brake system every year.

You know, even sitting in the garage it's going to collect moisture. The other brake fluid that is probably best used if it's just for race and performance application is a DOT 5. A DOT 5, when it first came out, a lot of guys were grabbing it because they thought this is a great thing because it's silicone-based. If you spill it on your car, spill it on your painted surfaces, it won't interfere with the paint. The silicone in it wouldn't rot or interfere with the seals.

However, that fluid is a lot more compressible. And what that means is when you're actually applying the brakes the fluid has some compression to it and it's not compatible with water. What that happens then is the water tends to pull in the brake lines and actually cause rust or corrosion pockets within the brake system. Most brake aftermarket brake manufacturers won't honor their warranties if you use a DOT 5 fluid. So, if you're putting in brake upgrades, performance upgrades, you really wanna consider using DOT 3 or DOT 4.