![Wink ;)](./images/smilies/icon_e_wink.gif)
I use Asda's cheapest 'smart price' mineral oil myself. Some folk use semi-synthetics with no problems.
Just avoid car type synthetic oils with 'anti friction' additives, as they make the Cub's clutch slip like billy-o (car clutches aren't immersed in the oil like bike clutches) . Cheapest is actually best really!
![Very Happy :D](./images/smilies/icon_e_biggrin.gif)
Change it every thousand or so miles (no worries if it goes a bit over)
Until you get to know your own bike's oil habits it's wise to keep an eye on the level every few days, especially check it after a long A-road blast.. Some high-mileage Cubs can burn oil at sustained high speed cruising, and there's not much in there to burn! Others never use a drop between changes, just get to know yours to be on the safe side!