Does anyone here use fuel additives to their tanks to prevent fuel line freezing?  How is that for a dog-days of August question? If so, what do you use and when?  If not, then why not? Just thinking forward to winter in my new to me turbo Mooney.  Here in the the far North of the USA, we sometimes get day time high temps in the minus teens, but often in the single digits - on the ground.  And of course colder at altitude.