Peter James replies: After trying many products for machine surface protection, my favorite is still Johnson’s Paste Wax and lots of it. In situations like yours, I apply it in a thick coat and do not rub it off until summer comes. When working with wood that is damp or wet, I smear an extra coat on before I start and then clean the machines after I am done and then put on another heavy coat.
The motors should be alright to start at the temperatures you indicated, but you may want to run them for a few minutes to let the belts and bearings warm up before you use them. The oil in the gear boxes of machines like planers and air compressors can get thick and not provide proper lubrication, but again run them with no load for a few minutes to warm them up.
Bob Couch replies: I feel your pain as I had a similar shop situation for a few years. However, I did have some heat via a unvented blue flame propane heater that I could warm the shop up with prior to any work. The problem with this type of heater is that it produces one gallon of water for every gallon of fuel burned. My machines were all covered in sweat until I started running a dehumidifier alongside the heater.
All that said, I tried several products to further avoid any rust, but in the end, I used Butcher’s Bowling Alley wax on all metal surfaces and I covered them with old bath towels when they weren’t in use. This wax can be hard to find but even with a well heated shop today, I still wax my machines 2-3 times a year with the Butcher’s. I don’t think temperatures in the lower teens is too bad but I wouldn’t go any lower than that.