The fluids used in Hydro-Gear products have been carefully selected, and only equivalent, or
better products should be substituted. Typically, an engine oil with a minimum rating
of 9.0 cSt (55 SUS) at 230°F (110° C) and an API classification of SL is recommended. A 20W-50
engine oil has been selected for use by the factory and is recommended for normal operating
temperatures. Biodegradable oils are not approved for this unit as they degrade too quickly
while in service.