Can You Mix DOT3 and DOT4 Brake Fluid?

By Staff WriterLast Updated Mar 27, 2020 2:35:52 PM ET

DOT3 and DOT4 brake fluids should not be mixed. The two can react negatively with one another and cause corrosion of a vehicle’s brake system. They also have significantly different boiling points, with DOT4 having a higher boiling point than DOT3.