I was out the other day on my bike visiting a few Stihl dealers for parts. Hearing how great the Stihl engine oil is supposed to be, I picked some up. In fact, I picked up two kinds. Stihl High Performance Engine Oil (orange bottle) 0781-319-8015 6-pack of 6.4 oz. bottles for $7.99 (High buck!) Stihl Low Smoke Engine Oil (black bottle) ISO-L-EGD/FC 0781-319-8040 12.8 oz. for $2.25 I asked the dealers what the difference was between these 2 types of Stihl oil and they didn't know. So I'll ask the same question here: What is the difference? If one is "low smoke" does that make the other "high" smoke? I notice the Low Smoke oil in the black bottle meets ISO standards while the other type in the orange bottle does NOT state that. Is the orange bottle stuff made to the same standards or what? Yet it cost more. What gives? What do you Stihl guys use and why?