It's not heavy, the oil stems shrink and let a little oil past. You really don't notice it. Sometimes i get a tiny bit of bluesmoke on startup but it's nothing. To be honest on the motorway you use naff all. Recenlt did from South Wales to Huddersfield then to Blackpool then back to Huddersfield and back to Wales and didn't use a drop of oil!
I am going to try abit of Forte Oil seal conditioner next time I change my oil to see if it stops it as I've heard good things about it.