I’ve been long wondering about replacing 50/50 antifreeze with pure water for long distance summer drive with a loaded 745 turbo. I’m not sure if it’s necessary or even beneficial or not. Today, I came cross this website. It looks interesting.

http://www.engineeringtoolbox.com/ethylene-glycol-d_146.html

Summary from the data on this website:

• Heat capacity: (0.865 vs. 0.963) - --- (50% antifreeze compared to 20%)

• Flow increase for 50% ethylene glycol solution compared with water: 14% (I assume for the same amount of heat transferring)

• Dynamic Viscosity: 0.7 vs. 0.48 (50% antifreeze compared to 20%)

• Boiling point: 107 vs. 100 (50% antifreeze compared to 0%)

So, conclusions?
• Pure water will keep your engine cooler (significantly?) ---- good
• Pure water has lower viscosity, better for flow? ---- good
• Pure water has lower boiling point, hence higher operating pressure ---- bad

I will have about 500lb of payload (diver and passengers weight), 800lb trailer (total weight) and a cargo box on top. The car is a 91 745T with 140K miles, well maintained. My question is: Is it a good thing to consider? If there is significant benefit going this way, I wouldn’t mind the mess to change over just for the summer trips. Let me know if this makes any sense of I’m just out of my mind. Thanks. Erwin