ISO 68 is All-season mineral hydraulic oils created on the basis of highly-purified basic oils with a high viscosity index and a zinc-free (low-ash) additive package for the most full compliance with specific operating requirements of modern high-load and heat-stressed precision hydraulic systems, including the ones equipped with servo mechanisms and servo valves used in industrial and mobile equipment for which the manufacturer recommends using “zinc-free” hydraulic oils. They contain zinc-free anti-wear, anti-oxidising, anticorrosion and antifoam additives and a viscosity modifier.