From what I read, the valves are for a VIS (Variable Intake System) system. The diesels don't have it, but the V6s do. There is a valve on the V6s for traction, built into the throttle body. I don't think the diesels have one of these either.
check crank case oil seal and the bottom pully it leaaked on mine for ages till i found out where it was coming from and the oil had eaten away the main pully as the center of it is rubber and it will perish with the oil
There's no signs of any oil leaking on mine though. But lets not forget that rubber perishes over time as well as mileage. The past 2 winters might have accelerated the ageing process of the rubber going from something like -18 up to the running temp of the engine is a big temperature change. Doesn't hide the fact the car is out of action till its fixed this week, push bike out again in the morning!