Originally Posted by birddseedd
I do not understand the concept of mixed fuel in a 4stroke.
Stihl (among others) makes an engine they call 4-mix.
It is a 4 stroke engine, with valves and all, however the fuel is sucked through the crank case just like a 2 stroke engine, so there is no oil sump.
It has the lower emissions of a 4-stroke (less unburned fuel in the exhaust), but no oil changes.