Converting a vehicle’s brake system from DOT 5 fluid to DOT 4 fluid necessitates a complete and thorough overhaul. DOT 5 is a silicone-based brake fluid, whereas DOT 4 is a glycol-ether-based fluid. These fluids are not compatible, and mixing them can lead to serious brake system failure. The process involves completely removing all traces of the existing DOT 5 fluid, replacing certain components, and ensuring the system is properly bled.
The impetus for such a conversion typically stems from issues related to DOT 5’s inherent properties. While DOT 5 does not absorb moisture like DOT 4, which reduces the risk of internal corrosion, it also compresses more easily. This compressibility can result in a spongy brake pedal feel. Furthermore, finding DOT 5 fluid may be more difficult and expensive compared to the more commonly available DOT 4. A conversion, therefore, may be desirable for improved brake feel, easier maintenance, and potentially lower long-term costs.
