Hi guys, Changed the oil in my mates 2012 1200 Sportster. Seemed to take a lot of oil, seemed like it wanted more than the book recommended, even after checking with the dipstick when hot. Got it to about halfway up the dip stick. Probably about 3L of oil? Anyway, that is besides the point but thought it might help. He left my place, all good. Rode his bike a few times then went to America for a month. Upon returning from the states - he checked his oil and there is NONE on the dip stick. He checked the oil drain plug, still there, no leak. He checked the oil filter, nothing leaking here. Apparently there is oil sprayed on the rear wheel/fender. Any idea what the hell is going on here? Also - where is the oil pressure relief valve? A guy on a HD forum suggested "Wet Sumping". This seems to match this description. Anyone got any ideas?