The performance of hydraulic brake fluid in vehicles is of vital importance to ensure an efficient and safe braking system. Over recent years, the use of discs all round has become much more prevalent, brakes have become “buried” inside the wheels, under-bonnet spaces have become more crowded and consequently hotter. Also car performance has risen dramatically.
Brake fluid specifications
Brake fluid is required to meet a number of international standards; for example FMVSS 116, issued by the U.S Department of Transportation – hence the reference to DOT. Fluids are assessed on their temperature stability, chemical compatibility with materials, corrosion resistance, lubricity and wear, with the most critical parts of the DOT standards relating to the behaviour of the fluid at extremes of both high and low temperature.
Fluid performance
Brake fluid is hygroscopic, that is it has a tendency to absorb water. This Increased moisture content in brake fluid has the effect of lowering the boiling point. The minimum DOT standard “wet” boiling point is set at 140°C for DOT3, 155°C for DOT4 and 190.6°C for DOT5.1. The greater the percentage of water content in the fluid, the lower the boiling point of the fluid becomes with the consequential deterioration in the performance of the braking system.
Delphi Universal DOT 3
Delphi Universal DOT3 is ideal for older vehicles. With a typical dry boiling point of 254°C, it exceeds the minimum DOT3 standard of 205°C and with a typical wet boiling point of 150°C combined with a high level of resistance to water absorption, Delphi Universal DOT 3 is one of the highest performance DOT 3 fluids available. It fully conforms to FMVSS 116 DOT3 and SAE J1703.
Delphi SUPER DOT 4
Most of today’s vehicles are originally filled with DOT 4 brake fluid on the production line. With its high boiling point, excellent lubricity and impressive viscosity, Delphi DOT 4 meets or exceeds the original fill requirements of leading vehicle manufacturers. Its typical dry boiling point of 270°C and typical wet boiling point of 170°C far exceeds the minimum requirements of the DOT 4 standard (230°C dry / 155°C wet), and provides an extended effective braking performance period. It conforms fully to FMVSS 116 DOT 4.
Delphi ULTRA DOT 5.1
Delphi DOT 5.1 has been specifically designed to cope with the demands of extreme driving conditions, high performance vehicles and the specific vehicle requirements of ABS braking systems. With its impressive boiling point characteristics (typical dry 271°C / typical wet 184°C) and a maximum viscosity at minus 40°C under 800 centistokes, this technically advanced synthetic fluid provides the ultimate in road-going braking at all extremes of temperature and vehicle performance. Delphi DOT 5.1 also conforms to the requirements of FMVSS 116 DOT 5.1 and can be mixed with DOT 3 and DOT 4 fluids.
Delphi LHM +
This premium performance mineral-based hydraulic fluid has been specifically developed for use in vehicles requiring this type of fluid, such as some Citroëns. This fluid contains special additives to protect against pump wear and to give excellent rust and corrosion protection as well as prevent sludge formation and consequential filter blocking. A high viscosity index, particularly at low temperatures, gives excellent flow rates throughout the system, together with impressive film strength and fluid performance. It is formulated to meet the higher specification requirements of ISO 7308, Ford ESN M6C59A and Citroën LHM B71 2710 (Post 1985).
Note: Delphi LHM+ mineral-based fluid is not compatible with hydraulic systems requiring a glycol-based fluid. To differentiate it, it is dyed green and system components which use mineral-based fluid are colour coded green.
Delphi Racing Performance Brake Fluid
With top of the range performance in the key areas of boiling point (typical dry 310°C / typical wet 202°C), compressibility, lubricity and water tolerance, Delphi Racing Fluid is ideal for all racing applications, including Formula 1, Indy car and super bikes.