No, most brake fluids are glycol-ether-based, not petroleum-derived. Petroleum-based DOT 5 fluid exists but is less common.
What Is Brake Fluid Made Of?
Here are some of the main Ingredients of brake fluid:
Glycol ethers:
This is the main part of brake fluid. It’s like the backbone.
Glycol ethers help the brake fluid push against the brakes when you press the pedal.
This is what makes your car slow down.
Borates:
These chemicals help the brake fluid boil at a really high temperature, which is important because if brake fluid boils, your brakes won’t work as well, and that’s dangerous.
Dyes:
Brake fluids come in different colors.
These colors, made of dyes, help people know what kind of brake fluid they have.
It’s like a label.
Anti-oxidants:
These are like protectors for the brake fluid.
They stop the brake fluid from going bad over time, that helps keep your brakes working smoothly.
Water Absorbers:
Even though brake fluid helps your car stop, it doesn’t like water.
Water can make brake fluid less effective.
So, brake fluid has special things called water absorbers to keep it dry.
Types Of Brake Fluid And Their Base
| Brake Fluid Type | Base | Common Use Cases | Boiling Point (Dry) | Boiling Point (Wet) | Compatibility |
| DOT 3 | Glycol-ether | Older passenger cars, non-ABS vehicles | 467°F (242°C) | 284°F (140°C) | Compatible with DOT 4 and 5.1 |
| DOT 4 | Glycol-ether | Most modern passenger cars, some light trucks | 475°F (246°C) | 311°F (155°C) | Compatible with DOT 3 and 5.1 |
| DOT 5.1 | Glycol-ether | High-performance vehicles, ABS vehicles | 500°F (260°C) | 354°F (179°C) | Compatible with DOT 3 and 4 |
| DOT 5 | Silicone | Motorcycles, racing cars | 569°F (300°C) | N/A | Not compatible with other types |
DOT 3, DOT 4, and DOT 5.1 are the most common types of brake fluid.
They’re all made from a special stuff called glycol-ether, which helps the brake fluid work well, even when it’s hot.
DOT 4 can handle higher temperatures than DOT 3, and DOT 5.1 is even better.
DOT 5 is different.
It’s made from silicone, not glycol ether, which enables it to handle high temperatures, which is why it’s used in racing cars and motorcycles.
However, DOT 5 doesn’t mix with the other types.
So, if you have DOT 5, you need to stick with DOT 5.