i just bought a scag turf tiger with the kawasaki 29 hp dfi engine and i want to know if it will be alright to use schaffer 15w40 synthenic oil in it. the manual said to use 30wt if possiable because the multi weight oils might have some oil compsumtion. i use schaeffer oils in all my vehicles and farm tractors and i didn,t want to have several kinds of oil on hand. i don,t want to hurt this engine so i would like your opinions.