In my old three wheeler, I'll admit to using quite cheap oil.
But the requirements of a total loss oiling system with ball bearing mains are quite different. However, I do significantly over oil - ie feed more through than the book amount.
Same reason as with the new engine, oil is cheap, rebuilds aren't.
Synthetics stay in grade for longer, so suit high mileage engines and long service intervals. Someone who is not doing high mileage is often better off with a good normal oil, but changing it more frequently.
