Being from Minnesota I've done my fair share of really cold, snow crunching (think below zero) winter flying and I've learned that preheating your engine makes life much easier.
It's that time of year again and many pilots will consider using preheat when the temp drops below freezing... This has always seemed odd to me so I did a little research.
Turns out some Lycoming models do need preheat below 20 degrees but for the vast majority of Lycoming engines the critical outside temp that requires preheat is 10 degrees not 32 degrees. My vote is we only preheat when temps are below 20 degrees.
In my research I came across a few good points to remember during your cold weather preflight and I've included the link if you're interested in brushing up on Lycoming cold weather ops.
"If flight is planned for bad weather, the preflight inspection should include observation of the relief opening in the engine breather tube so that any freezing of moisture at the end of the breather will not result in a loss of engine oil.
Once on board the aircraft, check the fuel-selector valve for freedom of movement. It may be frozen fast (this has happened), and you’d better find out while still on the ground.
Most of the time, we think of starting any engine as a very simple process. Just engage the starter, and listen for the engine to start purring. Unfortunately, when the weather turns cold, it is not always that simple. When dealing with a reciprocating aircraft engine, it may be essential to get a start on the first try in order to avoid icing over the spark plugs and making an immediate start impossible. In order to achieve a start on the first try, there are a number of factors to be considered. Those factors will be discussed in the following paragraphs."
Just tossing this out to the universe.
PS Did you know a fully charged battery will not freeze until -76 degrees Fahrenheit but a fully discharged battery will become a block of ice at 32 degrees?
