Don't think so. I've (knock on wood) never had overheating problems. I have antifreeze for the anti corrosion and lubrication the engine requires, definitely not worried about freezing as we're in Texas and the car sits in the garage when it's cold out. 50/50 is silly here.
I went to 20-50 because I don't drive the car cold (it warms up in the pits/grid idling beforehand) and at idle RPM I really don't want to see < 15 PSI. It drops down to 17ish according to my logs when it's heat soaked and I don't want to go any higher on the min wt.
Later
When was the last time you *really* did something with your Z to call yourself a Z enthusiast?