> the "One Gallon Plus" red plastic gas.... the wheel it sits in. It
> looks like the radiator fan exhausts through the area just above
> the spare tire, so I was a little concerned the can might impede
> cooling....

NO!!!  DO NOT DO THIS!!!

I did precisely this last year on a trip through VT/NH to carry a one-
gallon container of gas/oil mixture for a 2-cycle generator we
usually have along for jump starting, topping up the battery, etc.

I turned over the spare tire hollow-end up and put the gas can in
there.  I even put a little padding in there to prevent it from
moving around.

Well, it moved anyway and contacted one of the cooling pipes.
Conduction is always more efficient than convection, so ultimately,
the gas can's rupture disk did its thing and spewed gas all over the
spare tire and front of the vehicle.  Lucky for us, neither the fan
electric motor nor anything else provided a spark.

All we heard was a loud pop and then the gas reeked.  We quickly
pulled over and it took about half an hour to clean everything up
(although my spare was now nice and clean and lightly oiled. ;-)

Even if there was no conduction, as Dave Bogle pointed out, it gets
mighty hot under there and gasoline has a tremendous vapor pressure.
As a chemical engineer, I should have known better.

I now carry an empty gas can and a small bottle of 2-cycle oil and
mix in place if I have to.

-Karl

Karl and Kristina Bloss, Trexlertown, PA
'87 GL Weekender  "Beverley"
Mechanic list: http://www.enter.net/~bloss/vw/vwshops
Busses by the Trail - Oct 15-17, 1999: http://www.enter.net/~bloss/vw/bbtt
PA/NJ Vanagon owner's mailing list: http://www.onelist.com/subscribe/pavanagon