I bought a fuel can somewhere along the way--probably in Bolivia, but I don't really remember. Used it twice: once crossing the Andes between Chile and Argentina, once after a long battle with ridiculous headwinds in Patagonia. There were one or two other times when I was relieved to have a bit of extra fuel when I encountered unexpected detours, miscalculations, and closed fuel stations.

My point is not to tell you what you'll need or where you'll need it: only that if wandering even minor bits off the beaten track you'll probably be glad for a longer range sooner or later. Most of the time, my fuel can stayed empty because why bother? I normally have a 250 mile/400 km range, so draw your own conclusions about what you'll need.

Aside: in those Patagonian winds I discovered to my dismay how difficult it is to pour gasoline in a 60mph/100kph crosswind. Next time I'd carry a better spout, not just a funnel.

Lower octane gas is normally sold at higher altitudes, even here in the USA. This is not mysterious, and there are good reasons for it. My non-fuel injected bike kept chugging along up to around 15,000 feet, although with reduced power (duh). I had the most trouble with Brazilian fuel, which has a high percentage of alcohol. YMMV, but my worst fuel experiences have been in the EU (badly contaminated fuel along the Poland/Slovakia border) and Central America (presumed water contamination somewhere in Nicaragua). There's a lot of luck-of-the-draw involved.

I don't know where in the world you'll find leaded fuel these days, but it's not something I've worried about for quite a number of years--anywhere.

Hope that's helpful.

Mark