Re: Valve cover leak...
After going thru this thread, I decided to attack the pesky little seep of oil I'd noticed on our new (to us) XF. The leak was very small, just enough to give a whiff of burnt oil once in a while, too small a leak to even show up on the garage floor, and on the right (passenger) side of the engine. Found this out by just spotting some burnt oil on the exhaust manifold. So, cleaned her up good and pulled off the coils and decided to try just the breather cover first.
Not being one to use wire brushes on alloy parts, I found that some nylon neck cleaning brushes from my gun cleaning gear were a perfect size to clean the bolt holes and an AR-15 bolt brush, narrow end, fit the little grove perfectly. These brushes are impervious to solvents so I doped them up good with aerosol brake cleaner and in a few minutes I had a totally clean surface to apply the sealant to.
From my experience in trying to seal the stator covers on one of my late Harley V-Rods I decided to use GM Engine Sealant. It's grey in color and was the only thing that worked on the VR. GM part # is 88861417. I just squeezed enough in to slightly overfill the little groove, doped up the bolt holes and bolted it up. I used a nut driver handle on the Torx and hex bolts just snug "plus a little". That left a neat 1-2 mm bead of sealant squeezed out. After an overnight cure we took a little 300 mile road trip and the leak is gonzo.
Sure glad I consulted this thread before starting this simple job or I'd not have know about the aluminum bolts, light torque, etc. Great forum, thanks to all!