I'd trade
103's 110's bike to never see another oil thread.
However..... it is a new member asking who hasn't seen the derivative, repetitive and often religious answers that come from these things. So, for his benefit, here's a brief summary.
Sir, istnieje wiele możliwości wyboru
.
Yes, there are many choices (that's all the Polish I'm going to try). Any of the commonly known synthetic oils for use in the engine are going to be ok. Don't sweat it. I've seen automotive Mobil 1 on a shelf in Warsaw so you can probably get the 20w50 motorcycle version there too. If so that's a good one. It's generally perceived to be better than the HD branded oil you can buy from your dealership. But the HD oil isn't going to kill your engine. So don't lose any sleep any over it.
The Harley dealership will have a pretty good primary oil. If not use a good ATF (automatic transmission fluid). Preferably a synthetic. If you choose something else just make sure it is wet clutch safe.
Your transmission isn't anything special. It is just a gear box. Use a good gear oil. Preferably a synthetic. But the same kind of thing you'd use in a standard transmission in your car.