Compressor Maintenance for Winter
As the weather starts turning colder, there are things to make sure of when running a rotary screw air compressor mainly to do with fluids in the 
compressor itself. Screw compressors are built to run continuously, if they are not brought up to operating temperature they will build excess condensation which will freeze in cold temperatures.
Air Compressor Oil: The air compressor oil is affected by low temperatures. Oil tends to get thicker when it is cold, if the oil is aged or of poor quality the oil may become too viscous. Either way the thicker oil may prevent the compressor from turning easily enough. If the compressor is not serviced properly it is possible that the oil will contain a high level of water. This is not a huge problem at normal ambient temperatures but if the temperature falls too low this water can freeze in the oil, causing issues for the compressor at start up or causing damage to the compressor internals.
Air Compressor Condensate: Condensate is probably the cause of the biggest cause of problems for air compressors and cold weather. Condensate is formed when air is compressed and then cooled. Condensate is a mix of water (99%) and oil (1%).
Condensate tends to collect at low points within the compressed air system. These include, the compressor, separators, receivers, filters and dryers as well as in low points in the compressed air pipework. If temperatures fall low enough this condensate will freeze, blocking pipes or voids within the compressor, dryers, filters and pipework.
If there is frozen condensate in the compressor this can cause damage to the compressor, if it is in the filters or dryers again this can cause damage. If there if frozen condensate in the pipe-work, it can get blown to the downstream equipment, again causing damage to the downstream equipment including tools.
Air Compressor Dryers and Filters: Strangely the best protection devices for Air Compressors and cold weather are the dryers and filters built into your compressed air system. This is because this equipment removes water from the compressed air and this prevents water from freezing in the downstream pipework and equipment. So keeping your dryers and filters working effectively is important to protect the rest of your compressed air system.
Cold Weather Checklist:
- Regularly drain the condensate from your compressor. (this should be done daily anyway, but is especially important during cold weather to avoid freezing up overnight)
- Make sure that maintenance has been kept up on filters and dryers
- Use the correct viscosity synthetic oil.
Most Importantly: Read and understand your owner's manual for proper cold weather operation.