Hydraulic system and a method of operating a hydraulic pump

A hydraulic system, comprising a hydraulic system oil reservoir holding a hydraulic oil comprising:

• a. a lubricant base oil having:
• i. an average molecular weight greater than 475;
• ii. a viscosity index greater than 140;
• iii. a weight percent olefins less than 10;
• and
• b. an antiwear hydraulic oil additive package that is blended with the lubricant base oil;
• wherein the hydraulic oil has an air release at 50° C. by ASTM D 3427-03 of less than 0.8 minutes.

A hydraulic system, comprising a hydraulic system oil reservoir holding a hydraulic oil comprising:

• a. a lubricant base oil, and
• b. an antiwear hydraulic oil additive package that is blended with the lubricant base oil;
• wherein the hydraulic oil has:
• i. an air release at 50° C. by ASTM D 3427-03 of less than 0.8 minutes:
• ii. a sequence II foam tendency by ASTM D 892-03 of less than 50 ml;
• and
• iii. a number of minutes to 3 ml emulsion at 54° C. by ASTM D 1401-02 of less than 30.