What is the most commonly used brake fluid type for most vehicles?

The most commonly used brake fluid type for most vehicles is DOT 3 or DOT 4. These types of brake fluid are glycol-based, which makes them suitable for a wide range of vehicles, especially passenger cars. DOT 3 and DOT 4 fluids have a higher boiling point compared to DOT 2, which is important for maintaining braking performance under high temperatures. Additionally, DOT 4 has a higher boiling point than DOT 3, making it preferable for vehicles that may experience more intense braking, such as those used in heavy-duty applications or performance vehicles.

Many vehicle manufacturers recommend DOT 3 or DOT 4 fluids because they provide a good balance between performance, cost, and availability. DOT 5, on the other hand, is silicone-based and not compatible with the glycol-based fluids, making it less common for standard automotive applications. The other options, like ABC 3 or ABC 4, do not represent any standard brake fluid classifications recognized by relevant automotive authorities.