dr bob

Depends on your climate/operating conditions. 40-50% coolant concentration is a good general guidance. In extra-hot climate the ratio can be reduced to 25% coolant, with extra additives (Water Wetter), as the coolant actually reduces heat transfer a bit. At the opposite end, make sure the coolant concentration is adequate for the lowest temps the car might see. The protection ranges are shown on the data sheets and on the bottles themselves. Inadequate protection from freezing risks cracking the block.

In our current central Oregon high desert climate, I use 50% Zerex G05 in distilled water. Highest summer temp is about 105º. Coldest winter temp is probably -20ºF. The car hibernates in the climate-controlled garage (>50ºF) in the winters, but the freeze protection is maintained on the chance that something fails and the garage gets colder.

merchauser

I am sure you will get a host of differing opinions. I use 15% Zerex G-05 coolant and 85% distilled water for hot florida climate in all my cars. most anti freeze manufacturers say 50/50.

dr bob

I ran 25% in never-really-cold SoCal driving, and added one and sometimes two bottles of Water Wetter to keep the water pump lubrication and corrosion-inhibitor levels up. Be sure to compensate for the missing additives if you drop your basic concentration much below 50%. The cooling system metal and the water pump seal will thank you.

With adequate additives, there's no need to run coolant at all except for freeze protection..

vanster

I use the Porsche branded anti freeze. Not the cheapest of course

siscogts

I use glysantin g48 mixer at 50 percent with distilled water

Taguid

I've been using the Audi/VW pink Antifreeze 50/50 with Waterwetter. I get it from Amazon most of the time. $25.00 a gallon in concentrate