I'd advise against going much below 50% antifreeze concentration even in warm climates for the sake of corrosion protection. Mercedes recommends 50% concentration. I have 3 cars and all of them have some corrosion in the cooling system. I wish the previous owners took better care of it. As far as keeping coolant temps down, I have found on all 3 of my cars that the most helpful thing was to replace the thermostat. As thermostats age they usually don't open as much and make the car run hotter.

I would also strongly advise anyone against pouring anything that comes out of the cooling system onto the ground. Ethylene glycol is extremely toxic and is easily absorbed by the soil and ground water. Take that s**t to a recycling center please. I don't know about other places, but the local recycling place doesn't charge anything if you bring your coolant to them.

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2004 VW Jetta TDI (manual)

Past MB's: '96 E300D, '83 240D, '82 300D, '87 300D, '87 420SEL