How to Change the Brake Fluid From Dot 3 to Dot 4

Vehicle brake fluid is designed to resist boiling from heat caused by normal brake use. If the brake system is subjected to extreme driving conditions, such as mountain driving, or high-performance driving, the brake fluid may exceed its boiling point and begin to boil in the brake cylinders. This will cause sudden loss of brake pedal height and force that will put the driver and the car in danger. Changing the brake fluid from DOT-3 to DOT-4 fluid will help eliminate heat-induced brake fade due to the higher boiling point of DOT-4 fluid.

Things You'll Need

• Turkey baster
• DOT-4 brake fluid
• Drain pan
• Helper

Instructions

1. Clean and remove the cap from the top of the master-cylinder reservoir. Slide the fluid level sensor, if equipped, out of the reservoir and lay it aside. Suck out all of the old DOT-3 fluid using the turkey baster and dispose of it in a oil drain pan. Fill the master cylinder reservoir with clean DOT-4 fluid from a sealed container.

2. Position a drain pan under the first wheel listed in the bleeding sequence for your specific car. As a general rule, older, non-ABS vehicles with rear-wheel drive have a "right rear, left rear, right front, left front" bleeding sequence, while newer, front-wheel drive or ABS-equipped cars and trucks have a "right rear, left front, left rear, right front" bleeding sequence. Consult your service manual to be sure.

3. Push and hold the brake pedal with the help of an assistant. Open the bleeder screw on the brake cylinder (caliper for disc brakes and wheel cylinder for drum brakes). Allow the fluid to flow out of the cylinder into the drain pan. Repeat until the fluid runs clean.

4. Check the fluid level in the reservoir frequently to prevent air from entering the master cylinder when the level gets too low. Typically, it will take 1 quart of fluid per wheel to completely replace all of the fluid in the system. Repeat the process for the remaining wheels in the order of the bleeding sequence.