I would like to hear what kind of oil people like to use in lawnmower engines? Question is important for me now, because i have new B&S engine on my restored lawnmower deck, and i have spent now some restless nights, thinking about the right type of oil for new engine. I saw video in internet, and it was said that, if have old-school car engine, the "running in" time should use normal (not synthetic) oil, and after the "running-in" time is ready then can switch to the synthetic oil. So i bought B&S SAE30 oil, and filled my engine with that. I have still left this oil for one more filling. I will change the oil first time, when i have cut the grass once, and then another oil change again after one grass cutting. But then needs to know, what kind of oil might be good for the engine. Here in Finland, weather can be so cold that i will only think about multi-viscosity oils. Maybe 5w-30 ? I also saw one 10w-30 oil which is for diesel engines, but that oil have high zinc percentage which is good for old-school engines, so maybe i will buy that oil, it is not synthetic, but i think that old-school engine is most happy with the oil, which have high zinc percentage. But really i would be happy to hear about other peoples opinions about oils.