Big_Bird

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Amsoil Saber 100:1 mixed at 50:1 - gas was 93 octane

The engine was run for 6 hrs and almost 3 gal of fuel was burned. Engine
temperatures fluctuated around 220 degrees. Outside temperature was 30-32
degrees. Engine rpm with a 24 x 10 prop was 5900-6000.

After 6 hrs of running, there was a light carbon coating on the entire
piston, which scraped very easily. The dome of the cylinder was the same.
There was no carbon formation on the ring but the top of the ring has a
slight brownish cast. This reduced carbon over oil #1 may be a result of
higher engine temperatures (20 degrees F) or the oil itself. It was
interesting to note that the initial engine temperature shot up to 235
degrees F after running 15 min and then cooled down to the 220 degree F
range.

Amsoil 100:1 at 100:1. Gas was 93 octane.

The engine was run for 6 hrs and almost 3 gal of fuel was burned. Engine
temperatures ranged between 190-205 degrees F. Outside temperature was 30-32
degrees. Engine rpm with a 24 x 10 prop was 5680-5900. This drop in engine
rpm was very obvious. Either the engine is finally showing the wear of the
long accumulated runtime or the 100:1 oil mix did not give the ring seal of
the higher oil mixes or both.

After 6 hrs of running, there was a carbon coating on the entire piston
which was quite hard. The carbon was harder and slightly thicker than the
Amsoil Saber 100:1 mixed at 50:1. Hard carbon was also forming on the
cylinder head just above the exhaust port. Two spots of carbon were also
forming on the ring. Piston scuffing on the skirt started showing up after
this 6 hr run on 100:1. Scuffing was on both the intake and exhaust sides of
the piston. This may be due to the low oil or just to the 54 hrs of
accumulated time and the wearing of the wrist pin and bearings. I will be
interested to see if the engine rpm return in test run #10 when we go back
to the high oil ratio mix.

The photos are representative of 50:1 and 100:1.