BMW 2 SERIES F22 M235I & F20 M140I (3-BOLT) (14+)

 
The BR series coilovers use a large 46mm diameter piston in a 53mm diameter damper body to maximise oil capacity. As the damper unit opearates the oil contained within heats up. The viscosity of oil changes as its temperature varies which can lead to changes in the damping characteristics of the unit.