So, upstate NY. How well sealed and insulated is the garage - walls, rafters, doors? Will it be opened and closed during the winter or spring? Will vehicles be moved in and out?
What happens in Spring, when the machines are still very cold?
Has your choice of "cosmoline" set up firmly? It doesn't always do that, depending on temps and application thickness. What did you use?
Cloth covers are critical. Ideally there would be an air gap, but only a small one. Some parts of a machine should get extra protection - the taper attachment, the apron and gears, etc. Wrap the table on the manual mill.
Medium office binder clips, or clothespins and safety pins, work well to snug up your covers and reduce big air pockets.
Consider putting chicken 'brooding' bulbs, or goldenrods, etc, inside the machine cabinets. They are an inexpensive ceramic socket and reflector (though the reflector may not fit - the key is the high quality socket). The idea is to begin heating the machines from the inside-out as outdoor temps start to rise. That will be most critical when you get ready to uncover the machines. There are also 3M silicone contact heaters.