I am in agreement with those that say only use an oil container for oil.
If you are needing top up, just buy a qt and keep that in the car, then refill that.
I have a qt bottle under the hood of my truck. It has been in there for 3-4 years, I just keep topping it off. It is a thicker Havoline bottle that seems a little more heavy duty than some other oil bottles. I have some Castrol qt bottles that felt very flimsy and would not keep those in an area that gets hot, but would keep them in a trunk (in a baggie just in case it leaks).
If you had to use a different bottle, I am in the camp of using some type of sports drink bottle, those tend to be thicker bottles and tend to seal better than many thin water bottles. Just make sure to label it.