I define it pretty much the same way as your wife. The colder it is, the
longer a "couple" is.

Remember that the cylinders are designed for efficient transfer of heat from
metal to air and work that way in reverse. After prompting by our A&P, I
started looking critically at oil temperature and concluded that the 20
minute preheats we were getting from the FBO's big blower were not doing
much for the oil deep down in the pan. There is a lot of thermal mass in
the engine. As our A&P says, "Have you ever tried to thaw out a frozen
turkey on Thanksgiving morning?" The oil sump is at least that massive.

The cylinders are designed to operate at a range of temperatures and
accommodate the size changes. Sure, starting them cold, they are tight.
However, the 50 degree spread between a typical winter day and no-preheat
conditions is a relatively small part of the overall operating temperature.

The oil flow is the lifeblood of the whole engine however and proper
viscosity is critical. Trying to pump molasses around until the combustion
and friction (engine wearing out) heat warms it up enough to flow properly
is what really screws up your engine.

In the high cam Lycomings, the molasses also doesn't get up to the cams very
well.
--
Roger Long




G.R. Patterson III wrote in message
...


Roger Long wrote:

We've found that just a couple hours of electric heat on the pan alone
are
enough so oil temp comes up on taxi or in flight as fast or faster than
in
the warm months.

Ah. That answers my question. Now. How do you define a "couple hours"?
Two, or
some indeterminate number between two and five (that's my wife's
definition)?

In any case, I'll take my propane bottles. My CHT gauge will be off the
peg in
20 minutes when the OAT is 5 degrees F. Propane doesn't work well below
that
temperature, but then, neither do I.

George Patterson
If you're not part of the solution, you can make a lot of money
prolonging
the problem.