I have a quick question about adding some coolant to my Subaru Legacy 2001 sedan. I noticed it was a little low and wanted to add some before it gets much colder. I read online that there are two different kinds and I need use the right one or it will mess up your radiator? Also I think I need to mix the coolant with water before I add it right? Do they sell a premixed formula you can just pour right in? The car is old so it might have a leak, but I can't find anything on the ground and want to fill it up and see if it keeps dropping. Thanks in advance for any help.