DOT 3 From Wikipedia, the free encyclopedia "DOT 3 is one of several designations of brake fluid denoting a particular mixture of chemicals imparting specified ranges of boiling point. In the United States, all brake fluids must meet federal standard #116. Under this standard there are three Department of Transportation (DOT) minimal specifications for brake fluid. They are DOT 3, DOT 4, and DOT 5.1. DOT 3, like DOT 4 and DOT 5.1, is a polyethylene glycol-based fluid (contrasted with DOT 5 which is silicone-based). Fluids such as DOT 3 are hygroscopic and will absorb water from the atmosphere. This degrades the fluid's performance by drastically reducing its boiling point. In a passenger car this is not much of an issue, but can be of serious concerns in racecars or motorcycles. Deci 5.1, nu 5 care este intr-adevar pe baza de silicon.