On Sun, 03 Jan 1999 15:22:22 -0500, Huw Powell wrote: >I'm running Sierra (ethylene glycol?) at 50/50 (cold winters). Think >that might be it??? I think Sierra is <propylene> glycol; conventional antifreeze is ethylene glycol. I understand heat transfer is <less> good w/Sierra. In fact, they say not to use it if you're pulling a trailer.