rctom
Posts: 5206
Joined: 5/8/2002
From: Flower Mound (near Dallas),
TX, USA
Status: offline
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Here is a quote from the white paper. You really should read the whole section on "how 2 stroke oils work".
TF
"To understand how two-cycle oils work in your engine,
we need to cover some basic training on engine
operating conditions and oil formulation.
Outboard engines are characterized by their constant
speed, high output operation. They are usually
set at a desired high speed and continue at that
speed until the destination is reached and then throttled
down. Also, they are constantly cooled with
fresh, cool, non-recirculated water. Chain saws, on
the other hand, are a high action operation. They
are constantly started and stopped, used for short
periods and frequent overloads are its hard place in
life. Additionally they have smaller displacements
than outboards and are air-cooled. By understanding
how the operation of an engine can affect the oil
used and how an oil can affect the engine, we can
better appreciate the difference between a watercooled
two-cycle oil and one formulated for an
air-cooled two-cycle engine.
Water-cooled two-cycle engine oils require higher
levels of a heavy oil to prevent piston and cylinder wall
scuffing. Because of their high average piston temperature,
lighter oils evaporate too quickly from the
piston cylinder contact area. The heavy base oil,
which vaporizes at very high temperatures, resists
evaporation and remains in place to provide lubrication
to the piston and cylinder. Air-cooled oil
formulations must have much lower levels of the
heavy base oil than water-cooled engine oils. These
oils require only a small amount of heavy oil to provide
protection against piston scuffing and seizure at
peak temperatures. Heavy levels of heavy base oils in
an oil formulated for air-cooled engines can cause engines
deposits. These deposits form as a result of
incomplete burning of the heavy oil. The deposits can
cause piston ring sticking and can eventually plug or
disrupt the flow of the exhaust system, resulting in
power loss and possible engine damage. Detergent
additives should not be used in water-cooled two-cycle
oil formulations. When burned with the fuel,
detergents can produce an ash deposit in the cylinders.
This ash deposit can possibly foul spark plugs,
form exhaust port deposits which cause loss of power,
and possibly create cylinder hot spots that can cause
destructive pre-ignition.
On the other hand, the only way to protect aircooled
two-cycle engines against piston ring sticking
at their high peak temperatures is to include some detergent
additives in the oil formulation. Detergents
provide high temperature deposit control not available
from other additives used in the oil. However, in the
air-cooled engine, any ash deposits that could form
from the detergents are dislodged by engine vibration
and exhausted from the engine."
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RE: New 53cc engine now available - 
