Vaporized moisture condensed to liquid in a Separator contains acids, you
don't want that back in your engine.  Another advantage of a Catch Tank is
on-going monitoring of blow by quantity from oil change to oil change. If
the Oil Separator can be mounted in the forward plenum, the colder air will
make it work better.  Route the crankcase vent outlet over the exhaust to
vaporize any leftover drips for an even cleaner belly. The addition of a Ice
Slot about 6" above the breather outlet is also a good idea, see below.

PISTON ENGINE CRANKCASE BREATHER

"The following article was submitted by the
FAA, Aircraft Certification Office (ACE-116W)
located in Wichita, Kansas.
Recently, a small single-engine type
certificated aircraft experienced an engine
failure due to a reported frozen crankcase
breather line. The engine reportedly seized
after all the oil was lost (presumably
through the front crankcase seal). When
this happens on a single-engine airplane,
the lost oil usually obstructs the
windshield which further adds to the
pilot's difficulty in making a safe
emergency landing.
The FAA has repeatedly issued
Airworthiness Directives and Alerts on the
subject problem which can be adequately
resolved simply by ensuring there is a
number 30 (1/4") hole in the breather line
at least 6 inches (a maximum of 9 inches)
from the end of the line where it exits the
cowl. A 9-inch length of hose attached to
the end of the breather line will provide
equivalent protection if it can vibrate on
the exterior of the airframe. This
additional hose could possibly prevent oil
residue buildup. The additional hose
installation would be considered a major
modification and should be installed using
FAA Field Approval authority. If the
additional hose is installed, this would
preclude the need for drilling a number 30
hole in the breather line. Maintenance
personnel are encouraged to verify that all
piston-powered aircraft are adequately
protected with a method of crankcase
breather ice protection.
It should be noted that the ice actually
forms from moisture inside the breather
line during operations at below freezing
ambient temperatures. During crash
investigation of aircraft that have
experienced this condition, a cylinder of ice
is usually found in the crankcase breather
line that is a minimum of 2 inches in
length. An ice cylinder up to a maximum
length of 4 inches is sometimes detected.
Obviously, environmental conditions
suitable for airframe icing do not need to
exist for crankcase breather icing to occur.
Addition of the alternate ice hole will only
provide for an alternate breather outlet
when the exposed end of the line freezes
over. However, addition of the vibrating
hose should prevent ice from forming at
the end of the tube/hose.
Installation of the number 30 hole in the
breather line will sometimes result in an
oil streak on the interior of the engine
nacelle or on the fuselage or abrasion of the fuselage if the 9 inch hose is
used.
However, this is considered to be a small
price to pay for such significant protection
of the engine installation."

Steve Colwell  Legacy 550