What are the main components of brake fluid?

[StAlexa]

There are three types of brake fluid: 1. Castor oil-alcohol type, which is made by blending 45% to 55% refined castor oil with 55% to 45% low-carbon alcohol (ethanol or butanol). 2. Synthetic type, which is made by blending ethers, alcohols, esters, etc. with additives such as lubricants, antioxidants, rust inhibitors, and rubber swelling inhibitors. 3. Mineral oil type, which is made by blending refined light diesel oil fractions with thickeners and other additives. The method for replacing brake fluid: 1. Turn off the vehicle and open the engine compartment cover. Use a syringe to extract the fluid from the reservoir until it reaches the bottom. 2. Fill the reservoir with new brake fluid. 3. Use a jack to lift the vehicle, starting with the rear wheels, and remove the tires. 4. Locate the brake caliper's bleed screw and remove the rubber dust cap. 5. Use a wrench to loosen the bleed screw, attach a rubber tube to it, and connect the other end to a drain bottle. 6. Go inside the vehicle and start pumping the brakes. If the fluid coming out of the rubber tube is the lighter new fluid, the fluid change for that wheel is complete. Stop pumping the brakes, reinstall the tire, and repeat the process for the remaining three wheels. 7. After all four wheels have been bled, check the fluid level in the engine compartment reservoir. If it has reached the lower limit, add new brake fluid as needed.

[JuniperLee]

As a truck driver who's been on the road for years, I know brake fluid inside out. The main component is usually glycol-based liquid, like common DOT 3 and 4 types, which use glycol ethers as base fluids to transmit hydraulic pressure. They also contain various additives - anti-corrosion agents to prevent metal rust, anti-foaming agents to minimize bubbles (which could turn into vapor under high temperatures causing stiff, ineffective brakes). The key is boiling point - inferior compositions absorb moisture easily, lowering the boiling point. I learned this the hard way during mountain hauls when degraded fluid caused spongy brakes, nearly causing an accident. This fluid must be changed every two years to maintain system dryness. While brands vary slightly in composition, their core purpose remains: protecting the brake calipers and wheel mechanisms from seizing up. Safety isn't something to cut corners on.

[LaAlex]

I usually enjoy tinkering with car gadgets, and brake fluid composition is quite practical. It's based on a mixture of glycol ethers, with rust inhibitors and lubricating additives added. In the DOT series, DOT 3 is common, containing polyethylene glycol derivatives to enhance thermal stability—otherwise, high-speed braking could cause vapor lock. The boiling point needs to be high, preferably above 250°C. The formulation also considers low viscosity to prevent solidification in cold winters. Additives are designed to protect rubber components from corrosion—I once used poor-quality fluid, and the seals cracked, making replacement a hassle. Remember, moisture is the enemy; absorption can corrode the lines, so regular fluid checks are a must. When choosing fluid, check the DOT standard and match it to your vehicle's manual. Overall, the design ensures safety and reliability for the hydraulic system.

[StFelicity]

As a regular at old auto repair shops, I learned my lesson after experiencing several brake failures. Brake fluid is primarily based on glycol-type liquids, with additives to adjust performance. DOT 3 contains alcohol-ether compounds that easily absorb moisture, but it's cheap and practical. The formulation includes antioxidants to prevent aging and deposits. If the boiling point drops, the brake pedal feels spongy. After changing to new fluid, I always test-pump the brakes a few times before hitting the road. Remember not to mix different brands - ingredient conflicts can damage the system.