I use Amsoil Saber Pro in my saws and weedeaters. I use Amsoil Marine in my outboards. I mix both at 50:1. Oil for outboards is formulated differently because they are water cooled. Air cooled motors tend to run hotter and have different needs.
I used to use Amsoil 100:1 at 100:1 in the outboards, the theory being that you get a bit more power. And the old Scott Atwater outboards used to use their 100:1 oil. I switched to mixing it at 50:1 when it was pointed out to me that the old motors used a serpentine seal between cylinders that relied on the oil viscosity to seal the primary compression in the crankcases. They do seem to idle better at 50:1.
My employer has switched from mixing our own to the pre-mix fuel. Advantages are that the fuel is inherently stablized and there's no way to accidentally get the ratio wrong. They feel it is worth the increased cost. I figure the premix is close to 10x the price of mixing my own, but they figure it's cheap insurance, reducing the cost of maintenance and repair. If you only use the saw occasionally, the cost issue is probably not an issue.
The difference in lubrication between a modern 2-stroke oil at 50:1 and an older 2 stroke oil at 40:1 (or even 30w motor oil at 20:1 that was the diet of old 2 strokes before 2 stroke oils were developed) is negligible. However, the mixture has to be correctly adjusted to whatever blend you are using. Less oil in the fuel has the effect of fattening the mixture, so you may have to lean out the carb a bit if you switch to 50:1 or a pre-mix fuel.
