If you're sure it's burning oil, then there must be smoke.
As ARwrench says, if you didn't fit new valve stem oil seals, (and they're goosed), then you won't see smoke under acceleration or cruising, only when you back off and put your foot down again, usually from motorway speeds, ie if you're cruising at 70mph, back off, then accelerate again, you would see blue smoke at the back.
Very unlikely to be stuck rings if the engine has only done 4000 mls.
Giulia Ti Super Rep yet to finish. BMW 2000 NK to Ti spec