Steel type guns should be greased (weather permitting). Like the Mini, M1A, Garand, M1 Carbine.
Alloy type like ARs should be oiled.
As to where to grease, look it over, you'll see shiny parts where the bluing or other coloring has been rubbed off. That's where the grease goes.
If its cold then use a light weight oil. If its super cold, run dry.
CPT USAR Ret
USAMU Sniper School Oct '78
Distinguished Rifle Badge 1071