Hans,
This seal sticking stuff is obviously of concern to us, although we
haven't had any problem so far... but our engines are far from
having
thousands of hours. As a commercial product aiming to be
certified, we
CANNOT ask our clients to mix 2-cycle oil with the gas, it's simply
impractical. A separate oil tank for the sacrificial oil might be
a
solution but with marketing and safety drawbacks (what if an idiot
fills
the respective oil tanks with the wrong oil?). For the moment, we
are
experimenting with various oils and talking to oil manufacturers to
come
with the best possible single all-around oil.
We are also considering ceramic seals, but they are 5-6 times more
expensive than regular seals... we may offer them as an option,
we'll
see.
We'd love to have feedback from somebody who tried the Hurley
method of
feeding oil directly to the seals through tiny holes in the rotor.
Francois Badoux
I think a new engine is just as prone, it is the hours of inactivity
that allow it to happen.
Hans
In my humble opinion requiring Mobile One oil to be used is no hardship
for the average pilot. A small price to pay for the increased life, durability
and reliability of a rotary engine. Certified airplanes owners would snap up a
pure synthetic if it were available as it is proven to prolong the life of any
engine.
So far no synthetic oil is approved for certified piston engine as apparently
it has a negative effect on exhaust valves when used with high lead content
100 LL aviation fuel. Fortunately the rotary has no exhaust valves and Mobile One
seems to work fine with 100LL in a rotary. At least Tracy Crook is reporting no
problems using Mobile One and 100 LL which he is occasionally forced to do.
On the other hand I don't know if it is available around the world. If not
I am sure it would be more available around the world than a special aviation
oil designed strictly for the rotary. This is the age of UPS, Fed Ex and DHL
so cases of oil can be shipped around the world if necessary.
Mobil One is highly unlikely to cause the apex seals to stick. I do know
from my own test that it will survive 500 degree F while regular motor
oil goes to gum at around 300 degrees F.
Unfortunately there is no quick way to test Mobile One long term with
the variety of fuels likely to be burned in a rotary and that includes Jet A
and diesel fuel. If it were me I would specify Mobile One and forget mixing
two cycle oil with the fuel providing of course pilots are really dead
set against mixing two cycle oil with the fuel.
Has anybody on here had problem with apex seals sticking while using Mobile
One long term? I used it in my 2nd First Gen RX7 and it sometimes went
weeks with being driven. I am using it now in my RX8 but I only have 10,000
miles and it rarely goes longer than about two weeks without being driven.
Paul Lamar
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