I recently retired my 1974 lawnboy 2 cycle. Since I had such good luck with it, & this being the last year that they are producing the duraforce 2 cycle, I bought a lawnboy goldpro series (#10550) 6.5 hp 2 cycle. I always used the "standard" 2 cycle oil, mixed 32:1 in the old mower. I've read about synthetics, like amsoil, etc., that can be mixed 50:1 or higher. My questions--any advice on the advantages/disadvantages of these synthetics? Will using something mixed at 50:1 void my warranty? Should I use the standard 32:1 for a "break-in" period? Help!