I am not into chainsaws and power equipment, but this is a subject near &
dear to my heart
I run 20:1, and I prefer oils that are high quality synthetics and castor. People
have mentioned Yamalube 2R, 927, Maxima, Bel Ray and many more.
I run 20:1 in my watercraft race engines, because of documented dyno tests,
and manufacture testing (like Husqvarna MX), testing I completed while working
for a Watercraft manufacture, and racing experience.
Back in the 90's (in Calif. The Smog Law capitol ) The manufactures recognized
that when a watercraft started with a cloud of smoke, that was a bad look for
2-stroke engines (Yamaha was the worst). So many manufactured oils to smoke
less.
A common seizure on watercraft occurs on a short wot run and the engine suddenly
shuts off, and then restarts like nothing ever happened. The seizure is so benign,
that most customers keep riding their watercraft until the engine seized 10 to 20
more times and it finally doesn't restart.
The most common cause is an impeller with too much pitch. People think they can
just add a larger impeller and they will go faster. But the impeller loads down the
engine, holds the rpm ~1000 r's below peak hp and creates a lot of extra heat that
leads to detonation and finally preignition.
One of my riders made that mistake (while using 20:1 Maxima 927), and if he was
running 40 or 50:1 it should have seized on his first wot pass. If he had used a
tachometer he would have known the rpm was too low, and to take it back home.
But he didn't have a tach. He continued to test and made the situation worse. When
the engine finally seized, it locked up so hard that the impeller and driveline kept
turning. It twisted the drive shaft, and bent the drive shaft nearly 90' and shoved it
through the hull and it sank.
IMO, running 20:1 927 prevented the engine from seizing initially. But when it did
finally seize, it seized hard.
Bill M.