with a breather the engine vents oil fumes, the intake arm, the intake actually breathes in the oil so that it doesn't vent. Its prob just as bad cos your engine actually burns it.

THe best way is a catch can, but you can get defected for it like i was once. The catch can stores the oil so you don't vent or burn oil. Its a stupid rule that you can't have a catch can system, without getting it engineered, stupid cops.