Oil CASTROL Stransmax Axle lon life 75w-90 1L. Developed with Smooth Drive TechnologyTM, it is a fully synthetic rear axle fluid. It gives superior protection, particularly when driving in stop-start or extreme conditions, e.g. towing. This leaves a smoother axle operation and reduced rumble, resulting in a more comfortable ride throughout the life of the vehicle. Uniquely developed and approved by BMW for use in any and all BMW final drives fitted with standard (non limited slip) differentials. It is Castrol's primary recommendation for final drives in heavy commercial vehicles, and is approved by MAN, Scania and ZF. Fuel savings and emissions reduction due to its balanced viscosity and friction.