Question: what is the difference between dot 3 and dot 5?
Answer: While both fluids are glycol ether based, DOT4 contains a certain amount of borate ester which allows it to handle more heat. ... While DOT5 has a higher boiling point (500F dry/356F wet) than DOT3 or DOT4, DOT5 exhibits more compressibility than glycol ether brake fluid.