I have a 150cc china made dirt bike.i recently got a small crack in the engine casing but i have repaired it.i do not know what type of oil was alredy in the dirt bike but i want to replace it.i looked for 10w 30 in all the shops but none of them seem to have it so i got 10w 40 motorcycle oil...it is semi synthetic and is for four stroke bikes.would this type of oil be ok to use in the bike?lots of info would be great....thanks!