I don't recommend using oil instead of butter. There are different types of oils out there and some have more flavor than others that can alter the taste of the caramel. I also try to limit the amount of oil I use as much as possible in my recipes, and you would need quite a lot of oil for this recipe, half a cup. However, you could try using coconut oil instead of coconut cream, but I find that the coconut cream provides a nice creamy texture.