Al, I aree with you here. I have over the years owned a few aircooled
machines, and the kind of oil was supremely important.

Many years ago when I went to aircraft mechanic school, as engine
instructors I had  some really old timers who had experience and
knowledge accumulated I think beginning with the aircooled motorcycles
BEORE  Orville and Willbur Wright and then did Orvilles and Wilburs
first Annual Inspections  on their aircraft. I mean these guys went way
back and their accumulated knowledge about aircooled engines was
astounding. And the one thing they hammered into us greenhorn wanna-bee
aircraft mechanics was the importance of the oil as a cooling medium for
those engines - a means of scavenging the heat, transporting it, and
then disappating it. And the weights and types of oils, frequencies of
oil changes and the why's behind it all were hammered home. Same applies
to the aircooled VW engines, large and small. Water cooled is a
different matter. While the oil is definitely important in the
watercooled engines, what oil and how it works is affected by the way in
which heat energy is scavenged and transported by the water or coolant.
Operating philosophies and methods are definitely different.

Regards,

John Rodgers
88 GL Driver

Pensioner wrote:

>Fins?  YOU GOT FINS on your WBX crankcase?  Not likely that the specific
>heat of the two oils varies much but the mechanic was pretty much spot on
>with his advice for aircooleds.  They're really mostly oil cooled, with a
>large amount of heat being transfered via the oil to the case and sump and
>thence to the air.  If the oils have significantly different thermal
>capacity characteristics then ... well you get the idea.
>
>p
>
>
>