Do 50/50 only if you have freezing conditions. Other then that, you can go roughly 70/30, water/coolant. Then some water wetter for good measure too.

Water has better cooling properties then coolant does. The word coolant is actually a misnomer, in that it doesn't really help cool, but rather prevent corrosion and freezing from the water in the system.

Water Wetter also has some of those qualities that coolant offers. But I'm not sure how effective it is on it's own.

Here in SoCal, I can run 80/20 and not give a damn

 

I've gotten it at WalMart or K-Mart here in Jersey...I like the pre-mixed stuff, makes it easy to get the right amount

 

I run 80-20 the other way, 80 coolant, 20 water, for two reasons, 1) I don't tow and cooling is never a problem, even when at 100 degrees and 2) I dont make a lot of power so its just not that important right now.
It can get well below 0 around here in the winter, it depends on where you are in the world.

 

Mixtures over 70% antifreeze provide less freezing protection than the optimum 70/30.

Since dexcool is also glycol this parameter should not change.