I was just bone lazy & used engine oil in my Hitachi's. The opening rate wasn't too fast in mid winter when it was sub zero cold, but then I didn't push it untill it was fully warmed up anyway & the oil in the carbs thinned out nicely.
Never had flat spots from lifting too quick & the carbs were more stable on rough roads, so these things were just side benefits from being too miserable to buy the right stuff.