Just been given a Mountfield SP470 powered mower. This was given by a widow so she has no knowlege about the operation of the mower and there is no documentation. It has a Briggs and Stratton engine and is I guess 8-10 years old. What fuel do I put in ordinary unleaded or do I needsome two stroke mixture and if I do what is the ratio. I have not had much success on the net I was wondering if anyone here had any advice