Graphite or wax (rubbing a candle, or the stuff you can get at a machinists' supply in a little tub) works best.
Oils or anything viscous enough to work in a spray bottle tend to either gather dust / grit, or get thick as temperatures fall and make the assembly difficult to move. Some attack plastics, or remove the plasticizers from plastics, making them brittle, just the last step away from failure.
Some sprayable lubricants do work fine if you have a narrow minimum / maximum temperature range (and all-metal assemblies) where you live, but otherwise not the ideal choice; graphite and wax still work fine under that circumstance though.
Both are ridiculously cheap.