This ongoing thread on spare gas cans, internally stored fluids, fuel
composition impact on hot air engines and the justification for same leads me
to offer a few additional solutions.

1. Best solution, as I have posted in the past) is the Mercedes spare gas
can. Originally developed by MBZ as a safe solution to the problem, it is
mounted firmly (bolted in) inside the spare tire rim in the trunk of the
vehicle. 7 liters is an adequate reserve and I generally fill mine with
unleaded premium, add a storage additive and truck merrily away. My mounting
is also very similar to the MBZ approach if the Mercedes is operated rapidly
in the reverse direction. The spare tire compartment is protected by the
front bumper and massive frame rail (see the German article on Alistair's
site on crash test development by VW of the Vanagon - figures are in
english). The gas can is mounted within the rim of the spare. I have added a
bolt arrangement with T-handle to fix the can and wheel to the carrier pan
(unnecessary, but made the whole thing look more complicated and therefore
more pleasing to the eye).

2. Adding other fluids in time of crisis. I have been taking pictures of
combustion chamber interiors through the spark plug hole with a boroscope to
demonstrate to my son the impact of predetonation, detonation and extreme
detonation on high and low compression engines. The mottled appearance of
local aluminum melting has to be seen to be appreciated. Carry a spare gas
can! For a high tech engine, alternative fuels do damage (pre-detonation,
partially cracked fuel residues, potential contamination of Oxygen sensors,
fuel system components and the issue of liquid pooling in the intake
manifold). Anecdotal evidence of use without damage should be classified
along with the "if I don't look then it didn't happen" aspect of reality.

3. Its not enough. Indeed, as I have said, I have run a saddle tank of
nominal 12 gallon capacity (10.8 realized) for 19 years with no problem
except the false sense of security that I can wait for the next station.

4. Justification for use of auxiliary fuel tank. Gas crisis, American
Southwest, redneck concentration at rural gas stations in Alabama, Baja
California, Canadian Pacific Northwest, etc.

5. Justification for use of spare gas can. Ingrained response for diesel
Vanagon operators on North American land mass. Similar to the duck reflex
exhibited by motorcycle affectionados riding in the front seat area of four
wheeled vehicle when swarm of insects is clearly seen in front of windshield
at speed. BTDT often. After conversion to gasoline propulsion (and with
auxiliary tank) I have often had to rely on my spare can reserves in Wyoming,
Idaho, Nevada, Utah and California depending on the time of day of travel and
the quality of maps in my possession.

6. Other approaches. I first addressed the question of adequate fuel reserves
with my Safare Hightop '72 bus. For a variety of reasons I couldn't find a
safe place to store a reserve gas can within or without the interior. As I
was modifying the engine bay for installation of the Corvair engine and 4
speed manual  I found several underutilized areas. I fabricated two spare
tanks, outfitted them with several inexpensive low pressure fuel pumps and
plumbed them into the primary gas line. When I filled the main tank, I would
turn on the fuel pump to pump gas from the main tank into each of the spares.
I added a vent port at 1 inch from the top which went back to the main tank.
I would then pump until overflow to the main tank occurred. Then switch off
the pump until fuel was needed. When I was about to go empty in the main
tank, I would trigger the other pump on from the dash and refill the main
tank.

Oh well, fond reflections.

Frank Grunthaner