Maintenance of electric vehicle brake oil: 1. Replacement method: Open the oil storage tank cover, then there is an air hole protected by a leather cover on the disc brake caliper on the wheel, unscrew it, and you can drain the oil, then fill the oil from the oil storage tank and catch the oil with a basin under the air hole until there is no air bubble in the air hole; 2. Add method: first open the tank cover and fill it with oil, then unscrew the air hole at the disc brake slightly, step the brake to the end, and then tighten the air hole to refuel; 3. Then don't unscrew the air valve, step on the brake repeatedly, about 20 times, then unscrew the air valve, refuel and repeat until you feel that the disc brake is tight enough.