In   eleven years of editing the newsletter nobody has complained about  the
oil settling out of the fuel.  There are a couple of  reasons for this.
When you start the engine the fuel pickup in the  tanks is at the lowest
level generally so you might get an oil rich  mixture (as I recall oil
floats on the top of the fuel) but that is  soon returned to the tank by the
fuel pressure regulator  recirculating the fuel.  At idle it recirculates as
much as 90%  of the fuel flowing through the pump.


Paul Lamar


The  real question would  probably be best answered by those  engineers
closely associated with  2 cycle oil and it's miscibility  with aviation
or other
fuel.

Oil either mixes with fuel and stays  suspended (dissolved  for want of a
better word) or floats or sinks.  It really can't do  all three things.
It is
possible that it falls  out of  solution and then either one of the
other  two
is   possible.  (If my limited knowledge of physics is  still in  tact.)
If it
floats, it will not collect at the  lowest  part of the tank (the sump)
yielding  an oil rich  mixture. If  it sinks it will not float on top of
the  fuel
(unless  the various densities of hydrocarbons dissociate  with  each
other and
based on  their  density  relative  to water they either float or sink.

It might be an idea  to,  during your preflight, to vigorously shake the
wings for  two  purposes. 1, to mix the oil, 2 to check the continuity
of   the
spar.

Just a suggestion.

Rich

I have just tried  this, 5 ml 2-stroke oil in 500 ml auto gasoline  in a
glass jar. The  oil goes to the bottom. Part does dissolve quickly  but
the bottom  half of the jar has all the color. The bottommost layer  has
the  darkest color. It takes some shaking to get a uniform color. If   not
shaken, you will get a very oil-rich mix on starting.

Al   Rees

That is interesting Al. Thanks for doing that. Let it sit for  a  week and
see if it
settles out on the bottom again.

If  the pump is  pumping 20 gallons an hour
and 90% is recirculated on  start up and there is  1 oz per gallon in a 30
gallon
tank that  means there will be 30 oz in the  bottom of the tank.  Or.234
gallon
of oil. 18 gallons per hour divided by 60  is .300  gallons per minute. The
oil will
be sucked up in less than a  minute  and squirted back into the top of the
tank.

Check  my  arithmetic.

Paul Lamar



lets shed some  meaningful light on the subject rather than just background
scatter  lighting.

All 2 stroke oils are not the same some may dissolve easily  some not so and
some not at all and in fact might just be repackaged  standard oil.

The above experiment is great, as far as it goes, but it  would be great if
you would share the name and thpe of oil that you used,  was your gas auto
or  100LL.

These are facts that you have and  would shed light on that oil only. With
my midwest, there were only two  oils that were approved for use.

If others do similar experiments, we  can get a data base of which oils, and
which models of these brands  are good, bad or neutral.

Give us all the data that you have to make  your efforts worthwile.

Rich

I use Walmart brand that comes in a  gallon can. It is kind of grayish blue
in
color. It is for water cooled 2  strokes. If you mix a teaspoon full of half
and half with gasoline and set  it on fire in a cat food can it sparkles and
leaves no residue unlike  regular motor oil. I think that is a good test.

Most non synthetic  motor oils break down when baked in an oven at 500 F
for 30 minutes. Mobil  One held up best of the half dozen oils I tested.

I have been running  Mobile One in my rotaries for at least ten years.
Mazda says don't use  synthetics but they merely say they have not been
tested. Idemitsu sells  rotary engine oil that you can buy from Mazdatrix
and other  places.

Paul Lamar

-

Great, Paul, Thanks.

I wonder if there is any difference between the various oils (from
ridiculous to sublime in price)

Now what about the synthetic 2 cycle oils. Midwest, in addition to
specifying only one kind of synthetic-or semi-synthetic also approved a Mobil
Pegasus 50*** something (I thik 504) oil for use in their engines. That oil  was
developed for natural gas engines and apparently burns cleanly. I don't
know  about it's gasoline mixing properties. (I have a 55 Gal drum of it). The
Midwest  used an oil injection system similar to the Mazda but used it also
to lubricate  the bearings (roller) also. It blew it into the rotors for
cooling and then  tried to reclaim the unused oil before exhausting the rotor
cooling air.

Rich