I need to pour an additive into my radiator and having no radiator cap on the A6, I was instructed to pour it into the radiator hose. I see three hoses leading from the reservoir tank. Two on the front leading to the radiator and one leading to the back of the engine. I can't seem to find any diagrams decribing which hose leading to the radiator would be the one to pour into. Is it the larger hose leading to the bottom of the radiator, or the smaller one leading to the top?