Grinch

In my old SV's is about 5 litres of unlead petrol plus a full engine full of oil. Now its been in the bike about 2 years, and looking in the tank I can't see any rust. But I am concerned that something may have happened that I just don't know about, is there anything that i can do the clean this out and ensure all is well. Or do you think the fuel will be fine, I know it smells strong enough.
As for the oil I'll be changing that, and then starting her up. After checking the plugs plus dropping a little oil in the top of the pistions. Now would you say running it for say half a hour and then changing the oil again would be a good idea, or is this just over kill.