As it is called in our military, MoGas is to be burned in auto engines,
almost exclusively four stroke cycle, which operate on the ground.  This
fuel can be blended for altitude.  Gas sold in Denver will have a slightly
lower vapor pressure if they are doing the blending properly.  Vapor lock
used to be a problem in auto engines in the past and is still encountered
today, tho rarely.
Can you see the problem here?  MoGas is for automobiles not airplanes.
Anyone who uses auto fuel in an airplane is taking a risk which is admitedly
hard to quantify.  Especially so with the many blends of MoGas out there.  I
choose to pay the price for aviation gasoline.  There is only one blend
spec.
Fuel made for aircraft piston engine use is now almost exclusively 100/130
octane.  It is far different than MoGas.  It is made for your air cooled
aircraft piston engine and will enable you to fly at altitude with
confidence.  If you have a Subaru in your Lancair you may consider MoGas but
I would probably still burn aviation grade 100/130 or 100/130LL.
I wish to ask George to tune in on this discussion and tell me the reason
for the two octane rating system in use for AvGas.  I have never had a
satisfactory explanation.
Thanks,
Walter Dodson 1895740 IA;  IV-P coming out of Jim Griffin's upholstery shop
about the end of this month.  We gonna go play... and show off the machine.
Hopefully, it will be in the Lancair main hangar after Labor Day and thru
the third week of September for an avionics tweak and pilot training.  Can I
build you one next???
See you at the BBQ.