Here is a copy of a post I made a couple of weeks ago regarding this....Hope it helps:
< I have a 1980 Garelli Sport. It still has the original decals on the tank and the <bottom one says:
Engine: Garelli 50cc.
Breaking in Period: First 600 Miles do not exceed 20 mph max. speed. Mixture: 5 oz. oil per gallon of gas (25:1)
Thereafter: 4 oz. oil per gallon of gas (32:1)
Note: In the fuel mixture employ FIAT MOTO 2T oil or any good quality oil for two stroke engines.
For the gearchange assembly employ FIAT VS+30 (SAE 30W) oil.