This site (
http://www.summitracing.com/search/...Line-SuperCool-with-WaterWetter/?autoview=SKU) says, "SuperCool does not contain antifreeze and its freezing point is 32 degrees F or 0 degrees C."
Do you acutally need anti-freeze if the outdoor temp never drops below freezing?[/QUOTE]
In a word, yes. Anti-Freeze is only part of the job "Coolant" does. It also raises the boiling temperature above 212 degrees (plus pressurizing the system also raises the boiling temp.)
Now you may think you don't need to get the boil temp protection raised too much above 212. But you have to take into consideration ALL coolant temps at ALL times. For instance, the temperature of coolant that is next to the top of the cylinder wall can get VERY hot VERY quickly! You have to keep that coolant from boiling as well.
Then there are other jobs the coolant does like keep the interior components clean and corrosion/rust free. Coolant also lubricates moving parts like the water pump.
Most don't really need -21F freeze protection even if it gets that cold where you live because I doubt many people store their Spyder outside in that. As long as the ambient temperatures affecting the coolant in storage stay above the coolant freeze numbers you're good.
You can ride in temperatures (if you really must) that are colder than your anti-freeze limit becuase you've got a 2 cylinder heater moving and heating the coolant as you ride. If this doesn't keep your coolant above zero then you're a lot tougher than I am! :yikes: