Oil & Manual

Use oil per your manual typically 5w-30 or 10-30 synthetic DO NOT OVERFILL
Turn off unit to check oil levels per your manual.

Per Kohler
14kW is 100 hours
20kW is 150 hours
24-38kW is 120 hours
48-60kW is 150 hours
Manual air cooled units
http://www.kohlerpower.com/home/common/pdf/tp7092.pdf