Hi and welcome to mightyram. The vast majority of engine smoke and oil consumption issues are as a result of dead valve stem seals. This also fouls the oil like crazy. I would suggest taking the head off and getting it recon'd at a reputable machine shop. They'll let you know if the head is still viable (warped, cracked, corroded galleries, worn guides and valves/valve seats etc) I would recommend a full engine oil flush ( here's a link to my flush procedure - http://www.mightyram50.net/vbulletin...ll=1#post49592 ) You'll find it will break up deposits in ring landings, hydraulics and the heavy sediment in the sump. The G63B engine has some quirks to it but is a reliable hunk of metal, unfortunately like any engine they can only take so much abuse before they check out. Good luck and let us know how you go.