What is DOT4 oil?
2 Answers
DOT4 is brake fluid. Related introduction: 1. Overview: DOT4 is generally ester-based. The ester type is based on the alcohol-ether type with the addition of a large amount of borate ester. Borate ester is formed by the esterification reaction of low-polyethylene glycol or propylene glycol with boric acid. The boiling point of borate ester is higher than that of low-polyethylene glycol or propylene glycol, so it has better braking performance. Borate ester also has strong moisture resistance, as it can decompose the absorbed water, thereby slowing down the decrease in boiling point caused by water absorption. 2. Replacement: After one year of use, the water content in DOT4 brake fluid can reach 3%. When the water content in the brake fluid reaches a certain level, it will weaken the braking force and extend the braking distance. Therefore, it is generally necessary to replace the brake fluid every 2 years or 40,000 kilometers.
DOT4 is a type of brake fluid specifically designed for hydraulic braking systems in automobiles. It complies with the U.S. Department of Transportation (DOT) standards and has a higher boiling point than regular DOT3, ensuring more stable performance under high temperatures and preventing fluid vaporization during braking, which could compromise stopping power. This fluid also absorbs moisture from the air, reducing corrosion and rust within the system. Having driven many cars, I always remind myself to replace DOT4 brake fluid every two years or so, as prolonged moisture absorption lowers its boiling point, leading to spongy brakes and potential failure during emergency stops. Though it may seem insignificant, driving safety heavily relies on it. During maintenance, entrust professional technicians to replace it using the correct method, avoiding mixing with other types to extend the brake system's lifespan and ensure a more secure driving experience.
