GRM RR363 Heavy Duty Brake Fluid Brake Fluid for Rolls-Royce and Bentley vehicles specifying RR363 type fluid. GRM RR363 is produced using only the highest quality ingredients and is blended with special additives designed to enhance lubricity while reducing noise and corrosion. Formulated to be a replacement to Castol® RR363, which is no longer produced. Will not degrade rubber components. Meets manufacture specifications. Ships in 1 liter bottles.