Oil heaters with thermostats or Synthetic oil are recommended whenever the fan drive will be started with an ambient temperature around the gear drive of 20°F (-6.7°C) and below.  If hot water flowing through the tower maintains the ambient temperature above this limit for a period of time prior to start-up, then heaters are not required.
It is important that the oil is above its pour point temperature prior to start-up. Starting the fan drive when the oil temperature is below the pour point will result in no oil flow to the upper bearings and possible damage to internal components.   Very viscous oil can cause internal damage to the gearbox.
Synthetic oil has a much lower pour point than mineral oil.  The synthetic oils listed in our O&M Manual (viewable at www.amarillogear.com) may be used in our fan drives, without a heater, when the gear drive ambient temperature is   -20°F (28.9°C)  and above. Additional advantages are listed in our O&M Manual.
Below -20°F (-28.9°C) contact factory for recommendations.
Ambient Air Temperature               Recommendation
>20°F (6.7°C)…….mineral or synthetic oil
20°F (6.7°C) to -20°F (-28.9°C)….mineral oil with a heater/thermostat or synthetic oil
< -20°F (-28.9°C)…..Contact Factory