Big_Bird

My Feedback: (1)

Pennzoil TWC-3 outboard synthetic mixed 32:1. gas was 93 octane.

The engine was run for 6 hrs and nearly 3 gal of fuel was burned. Engine
temperatures fluctuated around 200 degrees F. Outside temperature was 24-26
degrees F. Engine rpm with a 24 x 10 prop was initially 6130 rpm for the
first hour, 6060 for the second hour then settled to 6000 for the remainder
of the run.

After 6 hrs of running, the carbon formation looked a lot like the Pennzoil
air-cooled. The 1/3 of the piston next to the intake port was shiny clean,
and a band of carbon equal to about 1/2 of the area of the piston ran down
the middle of the piston in line with the boost ports in the front and back.
The thickness of the carbon band was 5-10 thousands and it was black hard
carbon. The area directly in front of the exhaust port was shiny clean. The
dome inside the cylinder was without any carbon buildup. There was no carbon
formation on the ring or ring groves in the piston.

While the piston and cylinder look great, this oil mix really plugs up
exhaust systems with carbon.