Your tomos uses a #415H chain. It is a size exclusively used on mopeds. You should be able to get one for $15.00 and they will ususally cut it to the length that you need for free if you know how may links you need. (count the number of rollers in yoiur old chain). Regular oil is bound to fly off at high speeds. If you use a product made for chains such as PJ1 Chain lube it will stay put much better. No need to over oil either. only the rollers need to be lubricated.
Chris