It depends on how honest the oil company is and how expensive the additive package they use is. Then follows what you pay for the oil.
Provided the particles that pass through your air filter are not big enough to break through the oil film, the film should hold up and there should be almost zero wear.
So it follows that most of your wear comes from a cold start and the time it takes for the oil to reach all the lubricating areas in your motor. A thinner oil will get there faster, meaning less wear.
In general, it is accepted that a thicker oil, more viscosity will provide a better film, but in specific cases this may not be true.
Without any additives, whatsoever, a high quality synthetic base can have up to seven times the film strength of its mineral oil equivalent. But then they add additives which changes the whole package.
A dyno oil for example can have a film strength of 500 to 900psi, where a synthetic can range between 2000 to 4000 psi.
High performance motorcycle engines are high RPM, where flow is probably more important than viscosity.
All the oils that most folks here use, will have more than adequate film strengths, the first place you would see the problem where the oil film breaks down, is on your cam shaft lobes after several thousands of miles.
I play with oil in my Busa purely as a hobby and send a sample for analysis after each oil change. I am now using the second brand of 5W40 synthetic, which is way more expensive than anyone will ever need, but just doing it for fun. The previous one was a synthetic from ENI, the MotoGP sponsor and the viscosity polymer started breaking down pretty fast, so we will see how this one does when I have it tested.
My Prius (Yeah I have one, but I don't own a moped
) runs on Toyota 0W20, it has done 120,000 miles so far and I have never even opened the hood. They say these go for about 350,000 miles on the same motor and battery, but then there are transmission failures.
