[blucar]

OK, don't confuse me with facts, I have my mind made up.
It is a fact of life the heat expands, cold contracts.. Air intrainment in the coolant is not a good thing, the cooling effect of the coolant, regardless of what it is, is reduced with air in the system. After several recycles of the coolant via a recovery tank the air in the system is purged.
The volume contained in the recovery tank does not add anything in the way of cooling, it just minimizes unnecessary coolant loss and removes air from the system.
It is a fact that inexpensive plastic recovery tanks can be purchased from any major auto parts store, however, in many cases the space for a tank is limited, therefore a small 2" vertical tank is very desirable.