my 2 qm20 goes from strength to strength - i've changed the oil probably a couple of times more then necessary but it makes a lot of difference. My breather is just a tube down the side, puffs a bit, never bothered me, but i might run it round to the air intake when i got nothing better to do. My eng was pretty neglected when i got it, over 3 years now ive cleaned it up, fixed all the ancillaries and by running it properly, ie warmups, reasonable periods of running, regular running, running up to full power
when its warmed up for short periods, now it idles like an old harley, runs clean and reliable. Dont chuck your engine away without giving it a chance, they can be a pretty good engine if looked after.