I heard WD40 works well
WD40 sounds dangerous. Instead of greasy vaseline or oily vegetable Crisco my vet recommended Vitamin A or E oils on combs for frostbite and on legs for mite prevention -- with the added health benefit of making the skin, legs, toes, comb supple and soft instead of hard and flaky. We massage the oil into the leg feathers also - vet says its good for the feathers too and won't hurt to massage it into the leg feathers. We do it at roost time and the vitamin oils absorb into the skin overnight and there's no greasy mess like vaseline or vegetable oil on the feathers to make dust-bath dirt stick to the feathers! I love the vitamin treatments on our birds once a month - my hands are so soft after giving them massages - we only have 4 birds.