I bought a can of KOOL from o'reillys and split it between both of my machines, I left it mixed with antifreeze and it didnt change the freeze point but definately helped on cooling, the fan doesnt run as much on the 700 and hardly ever comes on on the 425. Another thing I just did recently was wrap the radiator hose that goes to the water pump with silver heat tape from home depo, this made a big diff, now the exhaust isnt heating the water so much.
Oh yea the KOOL was only like $3.00 a quart.

 

Engine ice works well. Check out Evans NPG+. After a while, i just got nervous about the whole additive and aftermarket antifreeze, and flushed my system, and put Amsoil Antifreeze in