Motul RBF 600 is a fully synthetic racing brake fluid to DOT 4, developed for the heat that competition braking generates. Under repeated heavy braking the fluid closest to the caliper pistons gets extremely hot, and if it boils the vapour compresses where the liquid would not, which is the long, soft pedal drivers describe as fade. A racing fluid raises the temperature at which that happens. RBF 600 is compatible with conventional glycol-based hydraulic systems, so it can be used to replace standard DOT 3 or DOT 4 fluid, and the 500ml bottle suits a full bleed on a typical car. It absorbs moisture readily, so change it frequently in a track car and keep the bottle sealed. Never mix it with DOT 5 silicone fluid.