Our 2006 has had an oil leak since we bought it less than an a year ago. It wasn't a serious leak, not dripping on the ground, just looked like a leaking valve cover gasket that produced a "wet"look around the gasket, but didn't drip down the side of the head or block.
This leak produced an oil scum on the final frame crossmember aft of the engine. Every time I washed the coach I found a dirty oily scum in this place and cleaned it off with Simple Green and paper towels.
This week I took the coach to Cummins NW for a differential oil change, check for slack in U-joints, and wheel bearing fluid level check. I also had them check the oil leak on the valve cover.
Cummins NW did a dye check on the oil leak and found it was coming from a missing oil filler cap in the top of the valve cover. I never looked on the top of the valve cover like I did on my boat, before I owned the motorhome. It's just because we don't normally look on the top of the valve cover since it's up near the floor of the bed, and weadd oil at the aft end of the engine block in the special filler for oil.
So, if you've got an oil leak that looks like it might be valve cover gasket, or you're not sure where it is coming from, make sure you've got your filler cap on at the top of the valve cover. I think I've been driving without one for most of the 15000 miles I've owned this coach, and it never leaked enough for it to make a significant impact on the dipstick. Blows me away I could have this 1 1/2" to 2" hole in the top of the valve cover and not lose more oil.
Its an FYI - but you might check to make sure you've got that filler cap on the top of your valve cover.
Former Owner, 2006 36MDDS
2010 Arctic Fox 22GK Travel Trailer
2007 Toyota Tundra