Use the lubricants that are recommended by the manufacturer. Tis Sadler Vampire's Rotamax is placarded against synthetic lubricants.
celerates with elevated temperature. Use a preheater only
when you plan to use the engine.
Which Oil Should You Use?
Do what the manufacturers say. They know what their
engines like. Don't try to make cheap oil into good oil by
adding additives; the good oil purveyors already came
up with the right mix. Air BP's John Copper once told me
that the topic of additives "…is mired in misinformation,
dubious science. If there is an additive that is good, it is
known by and available to the formulator." Remember,
too much of a good thing is a bad thing. Copper added,
"For every drop of additive put in, a drop of the actual oil
is removed."
Use the best oil you can afford, and remember that oil is
less expensive to buy and replace than any other component of your engine.
Also, don't assume just because one manufacturer recommends a particular oil that another manufacturer's engine
will like it. What's perfect for a Rotax won't be perfect in a
Continental. If you are running an auto conversion, join the
users group and find out what the majority of people are
using and what success they're having with it. (And don't
assume that the loudest guy in the group is always the
smartest guy.)
In a 2005 article, I noted that Roy Howell, an engineer with
Red Line Synthetic Oil, explained another big difference
between aero engines and auto engines. He said modern
car engines (and close-tolerance engines such as the Ro-
tax) have parts that are so close together that their lubrication is on the molecular level. Traditional aero engines,
because of their huge surfaces, also have enough room
between moving parts that a hydrodynamic layer of oil film
exists between the two boundary layers. In effect, one
part has its layer of molecular protection; then there's a
film of oil; then there is the other part, with its own boundary layer. It's a higher-friction environment because of the
relatively huge areas of oil that get pushed around; but it's
also a low-wear arrangement, since so many stresses are
spread over relatively huge areas.
The happy news is that frequent, long flights can extend oil
and engine life.
One last note: No properly broken-in engine ever was damaged by too-frequent oil and filter changes!
More information is available on these websites:
www.ExxonElite.com
www.AirBP.com
www.AeroShell.com
www.Rotax-Owner.com
www.PennYanAero.com
www.ChampionAerospace.com/products/oilfilters
www.SAE.org/technical/standards/ARP1400B.
Tim Kern is a private pilot and has written for more
than 40 different aviation magazines. He was a key
builder on two aircraft projects and has earned the
title of certified aviation manager from the NBAA.
EAA Experimenter
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