Non detergent oil
Detergent oils are meant to churn up particulates in the environment and trap them in an oil filter. moped crankcases don’t have oil filters, so the crap just stays suspended in oil all the time and leads to increased wear. Non detergent oils allow the crap to settle to the bottom, where it doesn’t hurt anything.
If you really want to stick to the letter of the law, people who sell lawn and garden supplies sell non-det oil for tractors. As there are no lawns in Sf, there are no tractor supply stores. Buy it on the internet, or just run det. oil.
It doesn’t really matter.