If items in your garage readily rust, then yes a protective coating wouldn't hurt (except be a dust/grime magnet) but I think I'd go with spray grease rather than a thinner oil of any type. The effect of a tiny bit getting inside (which means the seal is shot already?) and mixing with the jack oil is negligible. Makes you wonder though, why can't they put an accordion rubber boot over them? What brand of condoms take the most horseplay and come in a matching red or black color? Heh, am I allowed a colorful joke? "Hey Dave where did you get those jack spring covers?" Dave: "Your mom"