These five grades of premium-quality anti-wear ashless hydraulic oils with excellent stability are designed to meet the most stringent requirements of most all the major manufacturers and users of hydraulic equipment in environmentally sensitive areas. These oils are characterized by providing rust protection, low deposit formation, rapid release of entrained air and low pour points. They contain an effective ashless (zinc-free) additive system that has excellent resistance to oxidation at intermittent elevated temperatures as high as 500˚F and substantially help reduce long-term wear in high-speed, high-pressure vane and gear pumps. HD ashless hydraulic oils are compatible with steel, brass, zinc, aluminum, cadmium, magnesium, and copper. The additive system, on decomposition, will form oil soluble byproducts, whereas other antiwear additives may form oil insoluble by-products, leading to ash formation.