Well, there's preheats and there's preheats...
A quick preheat with a red dragon makes you feel warm all over (so does
urinary incontinence while wearing a dark wool suit) but doesn't do much of
anything except make the exterior sheet metal, fins, etc., temporarily
warm... The oil is still at ambient in the pan, and definitely ambient upon
entering the oil pump... And that great steel slab of rotating oil passages
they call a crank is still at -4 degrees, or whatever, to the oil trying to
flow through it - chilling the 'supposedly' warm oil quite nicely and
instantly...
notice that the crank has two or more 'ambient temperature equalizing heat
sinks' firmly attached......
Of course, you feel all warm and secure - if not actually doing a lot for
the engine - so I suppose that's worth something...

Same deal for an oil pan heater... You have a puddle of relatively warm oil
(often with a chilled center if it is the typical preheat) that will assume
crank/prop and case temperatures immediately upon flowing into the
passages...

If you read the aggregate wisdom of the alaskan/arctic flyers, you will see
that a preheat includes a solid hour - and usually more - of a red dragon
with the pedal to the metal, cowl blankets and prop booties, pouring the
heated oil (from a stove) into the engine and immediately starting...

Now the Reif, et. al., systems of cylinder clamps and pan pads can be
helpful IF they are on for a number of hours with an good, metallized,
insulated, blanket tightly wrapped, booties on the prop and hub, and no air
blowing up the exhaust, to allow the heat to soak all the way to the center
of the crank... Less effort than that and you are kidding yourself...


denny

"Dale" wrote in message "Dennis O'Connor"
wrote:

I started my engines this morning at -4 F... No preheat never do
That's the way this airplane has been treated ever since
semisynthetic, multiviscosity, oils came out.... Engines go to TBO
routinely...

Wow. To each his own. I would never start at those temps without
preheat, and I also used 15W50. I've also tried to pour it when it's
cold. G If it works for you, great.