What is the best brake fluid for classic cars?

What is the best brake fluid for classic cars?

The great thing about brake fluid is that there are only a couple of choices, so choosing the best brake fluid for your classic car is relatively straightforward!

Cars Manufactured Pre-1990.

Most cars manufactured before 1990 have a fairly basic brake system without anti-lock brakes. When these cars were new they used either DOT 3 (for the older cars) or DOT 4 brake fluid. Both are a mineral based fluid. DOT 4, is now the standard for brake fluid as it is  just an evolution of DOT 3 having better thermal performance.  There

Performance classics, post 1990 and cars with ABS.

ABS systems first started to be introduced as early as 1978 on big performance saloons such as Mercedes W116 models, but it wasn’t until the late 1980’s that ABS became a ‘standard’ piece of safety equipment. ABS allowed for much bigger discs and aggressive pads bringing braking performance to a whole new level, even in relatively hum-drum cars.  This meant that the brakes were producing a lot more heat. DOT 5.1 was developed to deal with this increased heat. It is a synthetic formula and will be perfect for 80’s performance cars such as 911’s and almost everything after 1990

Keep it fresh!

DOT 2, 4 and 5.1 brake fluid are all hygroscopic. That means that they take on water from the atmosphere and oxidise over time and use. This is less than ideal, so regular fluid changes will help keep the system free from debris and stop the master cylinder and callipers corroding from the inside out.

Here at Classic Project Shop we renew DOT 4 brake fluid every two years and DOT 5.1 every 3 years. It can genuinely save thousands of pounds in remedial work. If you don’t know the age of your brake fluid then look at the colour. It should be a light yellow colour. If it has started to bronze it is due for a change. The darker it gets the more damage it is doing to your braking system.

Historic Race Cars and Super Cars

If you need your brakes to perform at their maximum over and over again then there are specific brake fluids that have been designed to withstand high brake temperatures for prolonged periods of time such as MOTUL RBF 600. This brake fluid was designed to run in both steel and carbon systems allowing for repeated heavy braking without a loss of performance.

Is there anything better than DOT 4 or 5.1 on the market?

For Historic and vintage cars the other option is Silicon based fluid. This type of fluid is non-hygroscopic, meaning it does not absorb water and, therefore, will not corrode internal brake parts if left untouched for long periods of time.

It has a number of disadvantages though. Silicon fluid is more compressible, so can give the driver a feeling of a spongy pedal. It also reacts with other brake fluids, so can only be used in a completely fresh system, otherwise it can cause thousands of pounds of damage. It should also be noted that Silicone based brake fluid has not been developed for, or intended for, use in race applications.