The vapor pressure is always an issue. That is why 3 in 1 oil dries out and gets gummy. Ditto WD-40. Ditto white lithium grease. Ditto Lionel Lube.
I bought a 2343 a few years ago that had the gearboxes filled with white lithium grease which had turned to concrete. It took me 2-3 hours to dig out all the hard grease and clean the gearboxes up. Back in 1958 I was working in an appliance store fixing appliances. One of the appliances I fixed was hand mixers. The grease would harden and the gears would strip. White lithium grease.
I don't think any of us wants this type of trouble with out locos.