My coolant level is getting low and so I thought I'd top it up. Purchased some Prestone Antifreeze/Coolant which also says concentrate on it, so not mixed with water. The reservoir says coolant only so I assume that means just add the coolant, not mixed with water, and the system will measure it out as needed. However as there is coolant that is mixed 50/50 I am wondering whether or not what I put in the coolant reservoir is suppose to be the concentrate that I have or if I should mix it 50/50 with water first then add it.