Next time you go to suzuki, please get me his number:mad::mad::mad::mad::mad::mad:. Use SG, your engine is made for it. It isn't a matter of Neya oil hai, behtar hai. those guys at the dealership are illiterate.
you won't feel anything, but your engine will wear faster and next result is the tractor numa sound you hear from old suzuki engines.
it won't be overnight, but it will wear much faster. Go for API sg.
btw, plugs look good.