I use a bit of hand cream on my hair whie it is still damp. I comb it through then let my hair air dry. I wouldn’t use petroleum jelly as it would seem very dificult to remove it. I know of one lady who puts olive oil on her ends at night then covers them with a small plastic bag. I think she does it weekly. I have combed oilve oil into my hair then covered it with a shower cap (or a plastic bag). Next I warm a damp towel and cover my head then I put another one on top to retain the heat. I let it sit for up to 2 hours then I wash my hair and condition it. I do this about every 1-2 weeks for at least 20-30 minutes. It will take a few washes to remove the olive oil. I do this for deep conditioning. The hand cream works all year long on my fly away hair. I have medium length curly hair.