On Wed, 12 Nov 2003 21:24:17 -0500 (EST), (James
Lloyd) wrote:

For a cont. eng. with the oil tank,I have used a small 12 volt bev.
warmer and put it into the oil tank with an extention for the cig.
ligter plug to my car.It heats up the oil in about 6 mins.

Lloyd, very, VERY, bad practice. I deal with oils from a fluid power
standpoint, and the electric heaters for them have low "watts per
square inch" because of 2 things ... local high temperatures on the
element, and poor thermal conductivity of oil vs. water.

The 2 of these together cause oxidation of the oil which gets worse as
the heating element gets a buildup of partially burned oil.

And, if it does anything to (4 qts) of oil in 6 minutes, my guess
would be about 1 degree ... the calcs are not too hard with known
volume and wattage.

Typically from 10 to 30 watts/sq inch (lower for thicker, static
applications, higher for thinner, flowing situations) are used. Your
tank is static and probably has an SAE 50 fluid.

In contrast, long life elements (home water heater) are in the 40 to
70 w/in^2 range.

http://www.chromalox.com/Literature/TANK.PDF has much more than you
ever wanted to know.

If you use about 50 lbs/cu-ft and 0.5 BTU/lb/degreeF you will be
close.

The airplane you save may be your own ...