Today's motorcycle fuel is lacking in two of the most important extreme pressure, anti-wear and antioxidant additives – phosphorous and zinc. Why? Because a modern 4-stroke is not a two-stroke, and if these potent elements passed into an modern motorcycle's combustion chamber, they would flow out the exhaust and render the expensive catalytic converter on your motorcycle worthless.
Modern fuels are actually killing your two-stroke motorcycle, by faster wear and by burning hotter. The petroleum industry has developed a rating system that grades all oils. API SG oil is the last modern oil that is not restricted in the level of performance additives it can contain. Starting in the mid 90's, commercial motor oil and fuels has been neutered by a giant reduction in its protective components. In their place, the petrol companies have added friction modifiers. The result of all the friction modifiers is an SM-grade of oil that is safe for four-stroke engines with catalytic converters. For motorcycle use, most automotive motor oil provides limited protection and, worse, the friction modifiers wreak havoc on a motorcycle's wet clutch. Luckily, around the turn of the century, the oil industry realized what was happening and began producing motorcycle special engine oils.