HEES 46 is a biodegradable high temperature stable hydraulic oil based on synthetic components. It is environmentally friendly because biodegradable quickly. HEES 46 is an environmentally friendly alternative to mineral oil-based hydraulic oils. Degradability to CEC-L-33-T-82 (21 days) is greater than 90%. It is not soluble in water and, after leaks or oil losses, is largely retained in the uppermost layers of the earth and rapidly biodegraded there. HEES 46 is recommended if construction, agricultural and forestry machines are used under very severe operating conditions, such as outdoor temperature below -30 ° C or oil continuous temperatures above 100 ° C in the tank. After conversion to HEES 46, in the interest of operational safety, the oil filter in the hydraulic oil must be cleaned after approx. 15 operating hours to safely remove any dissolved dirt from the system due to the high cleaning power of HEES 46.