There is a product called HC-12, I goggled it and someone got vent temps of 22 degrees. It is compatable with R134a and R12a, you can use ether, PAG, or mineral oil. I think I might try it in my 280CE, R134 aint cutting it in FL where it is 90+ everyday.

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1985 300TD Turbo Euro-wagon
1979 280CE 225,200 miles
1985 300D Turbo 264,000 miles
1976 240D 190,000 miles
1979 300TD 220,000

GONE but not forgotten
1976 300D 195,300 miles
1983 300D Turbo 175,000 miles

http://i42.photobucket.com/albums/e3...e485-1-2-1.jpg