DOT 4 vs. DOT 5.1 Brake Fluid Technical Comparison Report
1. Product Performance Overview
1.1 DOT 4 Brake Fluid
- Base Composition: Glycol-ether based
- Key Applications: Drum/disk brake systems requiring DOT 4 compliance
-
Core Specifications:
- Minimum Dry Boiling Point: ≥ 230°C
- Minimum Wet Boiling Point: ≥ 140°C
- Corrosion Resistance: Meets OEM standards
1.2 DOT 5.1 Brake Fluid (Terzo-Tech Specification)
| Parameter | Value | Industry Benchmark |
|---|---|---|
| Performance Grade | FMVSS 116 DOT 5.1 | Highest safety tier |
| Dry Boiling Point | 289.2°C | 25% above DOT 4 |
| Wet Boiling Point | 197.2°C | 40% higher than DOT 4 |
| Low-Temperature Viscosity | 690 mm²/s @ -40°C | Ensures cold-weather performance |
| Water Content | ≤0.08% | Ultra-low corrosion risk |
2. Key Technical Differences
| Comparison Dimension | DOT 4 | DOT 5.1 (Terzo-Tech) |
|---|---|---|
| Base Chemistry | Glycol-ether compound | Modified polyethylene glycol |
| Boiling Performance | Dry: ≥230°C / Wet: ≥140°C | Dry: 289.2°C / Wet: 197.2°C |
| Compatibility | Mixable with DOT 3/DOT 4 | Restricted to DOT 5.1 systems |
| Moisture Absorption | High (requires regular flushing) | Low (extended service life) |
| Environmental Impact | Contains silicate additives | Silicate-free (reduces deposits) |
3. Application Recommendations
| Use Case | Preferred Product | Rationale |
|---|---|---|
| High-performance vehicles | DOT 5.1 | Superior heat resistance for racing/hilly terrain |
| Everyday passenger cars | DOT 4 | Cost-effective for standard driving conditions |
| Extreme climates | DOT 5.1 | Maintains fluidity at -40°C |
4. Critical Usage Guidelines
-
Mixing Precautions:
- DOT 5.1 must not be mixed with DOT 5 (silicone-based).
- Flush systems completely before switching fluids.
-
Storage Requirements:
- Store in cool, dry environments (avoid sunlight).
- Shelf life: 2 years (6 months after opening).
-
Compatibility Check:
- Always refer to OEM specifications.
- Recommend pre-flush with dedicated cleaning agents.
5. Product Upgrade Advantages (Terzo-Tech DOT 5.1)
- Enhanced Safety: 25% higher wet boiling point than DOT 4.
- Longevity: Reduced moisture absorption extends service intervals.
- Regulatory Compliance: Meets EU REACH and global environmental standards.
Maintenance Tip: Test moisture content annually (critical threshold: >3%).
