re syn or mineral it is best to run your new two stroke engine in on low ash mineral 2 stroke oil,oil that is readily available like castrol active 2t oil,it is low smoke and a well proven product, mix oil with unleaded petrol to eng manufactures specs
run in engine for 15 to 20 ltrs, this will ensure a good bedding in of the rings to the bore, a little bit of carbon on top of the piston also helps in a good piston to bore seal, when this done change over to posibly a syn oil low smoke oil, some thing that is readily available like sthil two stroke oil,this oil is also made by castrol, it is the same for four stroke engines run them in on the manufacturers instructions ie briggs & stratton sae 30 eng oil, if you run your four stroke mower in on car eng oil you will find it will become smokey from the exhaust on start up and will develope an oil consumption problem throughout its life rgds graham