This mixture has been round for over the 35+ yrs I have been baking I keep it in an old plastic container on the kitchen counter. I also keep a thick round (2") pastry brush nearby for brushing it on the pan. Don't store the bursh IN the mixture container.
I alwasy mixed it up w/my KA - wire whip for about 5 minutes - until it is light, fluffy like whipped cream. As it sits on the counter - especially in warmer weather - it will seperate some w/the oil seperating out on the bottom. If it's done that it's time to rewhip it.