When changing the lubricating grease in a geared motor coupling, always apply a full coating of grease to the teeth of the coupling. Never fill the coupling housing completely with a grease gun due to expansion of the grease as the motor comes up to running temperature.This expansion of the grease will apply internal coupling pressure pushing the motor shaft off magnetic center and onto the thrust surface of your bearing, causing bearings to overheat and lead to early bearing failure.

Even after hand packing the coupling, the motor should be run up to operating temperature then shut down and the grease plug removed to allow excess grease and pressure to be released. (Submitted by Wesley Jacobs, Director of Maintenance Services, Missouri American Water Company. Thanks Wesley!)

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From "Turbine Lubrication in the 21st Century"

As with existing turbine oils it is necessary to adequately maintain phosphates in order to ensure efficient operation of the system and an acceptable fluid life. The parameters that are of most concern are the increase in acidity, water content and particulate contamination level. When triaryl phosphates degrade, the most common result is an increase in acidity with little effect on viscosity change. Consequently, this latter property is not one that requires regular attention. Water and acidity, however, need monitoring. To date there are no specifications for used fire-resistant turbine lubricants but there is a tendency to adopt the limits already in existence for phosphate esters when used as turbine control fluids, i.e. a maximum acidity of 0.2-0.3 mgKOH/g.

More information about the book "Turbine Lubrication
in the 21st Century"