Test Each Others Brakes
I encourage ONYX owners to test each other’s brakes - it’s a great way to immediately understand how well-maintained brakes should feel. This has even helped a few friends who had no idea how badly their brakes needed servicing. Check out the ONYX RCR Front Brake Maintenance post to learn how to maintain your brakes properly.
ONYX DOT Brake Fluid
Your ONYX comes with DOT 3 brake fluid, but now you’re wondering-what else can you use? Can you mix them? What’s the real difference between brake fluids? Let’s break it down!
Brake Fluid Breakdown
Brake fluid plays a critical role in hydraulic braking systems by transferring force from the lever to the brakes. However, not all brake fluids are created equal. Here’s how they compare and whether they can be mixed in an ONYX.
DOT 3 Brake Fluid
- Type: Glycol-based
- Boiling Point: Lower than DOT 4 & DOT 5.1
- Moisture Absorption: Absorbs water over time (hygroscopic), requiring regular replacement
- Common Use: Older cars, motorcycles, bicycles, and light-duty vehicles
- Mixing: Can be mixed with DOT 4 & DOT 5.1
DOT 4 Brake Fluid
- Type: Glycol-based
- Boiling Point: Higher than DOT 3 (better heat resistance)
- Moisture Absorption: Absorbs water, but less than DOT 3
- Common Use: Modern motorcycles, performance vehicles, and hydraulic disc brakes
- Mixing: Can be mixed with DOT 3 & DOT 5.1
DOT 5 Brake Fluid
- Type: Silicone-based (NOT glycol-based)
- Boiling Point: Very high, does not absorb moisture
- Moisture Absorption: Does NOT absorb water (hydrophobic), but water can pool in the system
- Common Use: Specialty applications, military vehicles, classic cars (doesn’t damage paint)
- Mixing: DO NOT mix with DOT 3, DOT 4, or DOT 5.1
DOT 5.1 Brake Fluid
- Type: Glycol-based (not to be confused with DOT 5)
- Boiling Point: Highest of the glycol-based fluids
- Moisture Absorption: Absorbs water but performs better under extreme heat
- Common Use: High-performance motorcycles, ABS braking systems, heavy-duty vehicles
- Mixing: Can be mixed with DOT 3 & DOT 4, but NOT with DOT 5
Can They Be Mixed?
| Brake Fluid | Can Mix With | Cannot Mix With |
|---|---|---|
| DOT 3 | DOT 4, DOT 5.1 | DOT 5 |
| DOT 4 | DOT 3, DOT 5.1 | DOT 5 |
| DOT 5 | Only DOT 5 | DOT 3, DOT 4, DOT 5.1 |
| DOT 5.1 | DOT 3, DOT 4 | DOT 5 |
Which One Should You Use?
- For most motorcycles, e-bikes, and cars: DOT 4 or DOT 5.1
- For performance & extreme conditions: DOT 5.1
- For classic cars & military vehicles: DOT 5 (only if the system is designed for it)
DO NOT mix DOT 5 with other brake fluids! It is silicone-based and incompatible with glycol=based fluids. Mixing them can cause brake failure.
Bottom line: If you need to top off your brake fluid, make sure it’s the same type as what’s already in your system.