After learning that even a bit of leftover water can considerably reduce the freeze protection of the -50 F pink stuff, i was looking for some -100 antifreeze to pump into the block and increase the concentration of the good stuff. Couldn't find any locally but found -200 (!) from starbrite online. Its not generally cheap but there's a great deal for it through amazon. 14 bucks a bottle, You could dilute it 50/50 and still have -100 antifreeze! In case anyone else is interested in the stuff:

http://www.amazon.com/Starbrite-Anti...ze+concentrate

Ayuh,..... Up here where it gets Really cold, We winterize with Air, as it never freezes,.....