Mmm.......cookie good......Gut strings on double basses are commonly oiled as part of routine string maintenance. Oiling can help reduce the little "whiskers" that sprout from the strings that need to be trimmed off.
There is fancy bespoke string oil, but I use sweet almond oil from the grocery store as it makes my strings smell like cookies
Thats the no.1 lube for uprights.I don't play flats but I regularly use nose corner grease (external) for my plucking fingers. Works like a charm.