So, what does this brake fluid have in common with this coolant right here? They’re both made of the same substance, glycol. The formulations may be a little bit different and additive packages are definitely different, but with glycol, they’re both hydroscopic. In other words, they’re going to absorb water. So when you do a 50/50 mix of coolant, it mixes, it doesn’t separate out. Well, it’s the same way with water and brake fluid. Water will get into it and it will disperse. It won’t even out inside the mixture.
So keep this in mind when you’re selecting the brake fluid for the vehicle. And also a reason to recommend servicing the brake fluid, because over time, moisture will be absorbed into the brake fluid and change the boiling point. When you change the boiling point, well, you’re increasing the risk that you might have brake fade, and the fluid could boil when the brakes are applied heavily, going down a hill, or continuous application. So just keep this in mind when you’re servicing brakes.
So what’s the difference between dot three and dot four? Well, it’s actually the dry and wet boiling point. Dot four typically has a higher wet or dry boiling point than dot three, but there are other things to consider. It’s the viscosity of the fluid itself. Sometimes some brake fluids will have a different viscosity. So you may need to go with an alternative brake fluid for a vehicle. So make sure you’re checking that service information to what kind of fluid it requires. This is especially true on vehicles with ABS and electronic stability control, because if you don’t get it right, well, actual cavitation will occur inside the hydraulic control unit for the ABS. And when this happens, you get tiny little bubbles. Those tiny little bubbles can cause issues with the application of the brake pedal. In other words, it’s going to feel a little bit long or a little bit soft.
So keep this in mind about the wet and dry boiling point when you’re selecting a brake fluid for the vehicle or you’re recommending it to the customer. I’m Andrew Markel. Thank you very much.
This video is sponsored by Auto Value and Bumper To Bumper.
