HNBR is made via selective hydrogenation of the NBR butadiene groups which improves the temperature and ozone resistance considerably. Due to the polymer structure, HNBR offers both resistance to polar and nonpolar media. The selection for dedicated automotive applications depends on the ACN content which can range from 18% to 50% (this influences the swelling in oil), as well as on the degree of saturation (this influences the heat resistance). HNBR offers extraordinarily good mechanical properties and abrasion resistance. The operating temperature ranges, when in contact with mineral oils and greases from -30°C/-22°F to 140°C/284°F and for a short period of time up to +160°C/320°F. Special types can be used down to -40°C/-40°F.