Honda 4 stroke brushcutter.

I believe that the oil should be a quality SAE30 or equivalent. As for the oil change intervals, as the oil sump only holds a tiny amount of oil, change it as often as you can (within reason), as it'll get pretty contaminated quite quickly. However, as with most things, it will depend on how often, and for how long you use it, If it's going to be for half an hour once a week, then I'd just check the oil level every time you are going to use it and change it every six months or so.

Thanks very much for your prompt replys, it looks like it will be sharing the bulk drum of S.A.E 30 with the stationary engine collection.