Greasecar Kit in my TDI (didnt want to mess around). Building my own for 85 300D (tougher). No problems. I think Greasecar is the best bang for the buck, and definitely the best cold weather kit. You can make your own for cheaper, but is it worth it? I dont like wrapping copper coil. If it's cold, you want end to end coolant insulation. If just going with a blend, only in pre-1986 Benzes and with some sort of heat exchanger before IP. Arctic Fox makes one if you dont want to make one. I cant imagine more than 50 percent blend in colder weather, and definitely not in sub freezing. I had a B50 (yeah, biodiesel) freeze up at 24 degrees in a 300D.