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Old November 4th 04, 03:46 AM
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My Minnesota thoughts -

1) Preheat only before flying. Do not heat continuously or you will
have internal corrosion in the engine cylinders. Inside storage is
OK.

2) Preheat long enough to get the oil warm too. Do not just preheat
to get the cylinders warm.

3) Don't think you can get by without preheat "just this once" when
below about 32 deg F, especially if you have non-winter grade oil. It
is really hard on an engine as it takes quite a long time for the
crankcase to develop an oil fog if things are too gooey. Scored
camshafts and cylinders can be the result. I like semisynthetic oils,
although the starter engagement on your 150 may not like the extra
lubricity.

Engine lube systems are such that the bypassed oil from the relief
valve does not have good access to the heat of the cylinders. They
then become actually surprisingly slow to warm up - especially if the
oil is thick, since most of the oil flow bypasses the engine after a
cold startup. Try to cover any oil coolers so that the oil temp
eventually warms up to 180 deg F in flight to minimize condensation in
the oil.

4) Add small amounts (couple of tablespoons or so) of isopropyl
alcohol (yellow can HEET) to the tanks as a matter if principle when
it is below freezing. You may otherwise have small amounts of
dissolved water in the fuel come out of solution as snow when the fuel
is severely chilled. Beware of fuel that has been severely chilled
since its last filtering. On a long flight, this snow can block the
fuel screens. I know, it happened to me although it was about -20 deg
F. I know of others that have had the same problem.

Personally I don't like to fly below zero F, as a result of 4), but I
know others do it.