MS 261 - piston and rings after 60l/~15gal of alkylated gas + HP Ultra at 33:1

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LegeaDejului

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Hello, I'm pretty new on here, used to be a lurker until recently. So I just got a new MS 261 (ver 3/carb) this spring and scrolling around during that time (including that 400-500 pages oil thread, oh god) I noticed that the veterans on this site aren't big fans of this oil. "Smells bad", "dirty" are probably the biggest complaints. I've been using it for a couple of years now with no issues, and Motul 800 offroad for my bigger saws as they manage to burn it off better than the lower CCs and I could buy it pretty cheap. Never had any problems with the top or bottom end while running these oils, but I also don't run my saws 50:1 or let those crappy H limiters on and have the saw running lean "for the environment" (also running lean can create some nasty crust on top of the piston from the lack of proper washing/overheating, no matter the oil used or the ratio). So from day one this saw was 4 stroking with no load at WOT and cleaning itself up when buried in wood, not once was it used out of tune.

Random fact regarding this ultra oil, a lot of people kept mentioning how it's Castrol TTS. It's not, it's actually similar to Maxima Super M, which has 60% trimethylolpropane ester as it's base and the rest is other fillers/detergents etc (Ultra is 80-90% trimethylolpropane ester + rest detergents). It seems to be mostly used for turbine engine lubrication, which could explain it's high flash point, relatively low viscosity (sliding wear parts, like the top end loves low viscosity lubricants for optimal lifespan; rolling wear parts, like the bearings perform best with high viscosity - so it's always a trade-of) but great viscosity index (viscosity drops less with temperature than other higher viscosity oils with lower viscosity indexes).

Anyway, here are the pics (sadly I couldn't manage to take any pictures of the top of the piston, the flash just couldn't illuminate properly, but it did have a bit of carbon with proper washing pattern on the sides. Everything looks clean and well oiled, no deposits on the exhaust port walls, and even the machine marks of the rings themselves are still visible (the white line on the piston is the flash reflecting back, not a score mark). So what's my point? A properly tuned engine used with clean, good quality gas has more of an impact on how deposits react than any oil. Now if only the smell would go away... :crazy:
 

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