No, but over time oils loose their energy because it's old. Think of it like preserves, it lasts longer, but after a while the 'freshness' wears off. [Dried herbs and oils to me have a 1 year shelf life]
Casting a spell on a daily basis might be a little much, but you can do it provided you have enough energy to cast. It sounds to me however you're overdoing it on the spells. Sometimes spells don't work when you ask too much, casting for the same thing every day is like asking your parents for a puppy every day, they're going to get annoyed and start to ignore you. Once is typically enough.