Re: Oil in #5 plug ????
If you have oil on just the boot, I would say that valve cover gaskets are in your near future. If you have oil getting onto your plug, you have something more going on here. Without a doubt, it sounds as if you have excess oil entering into the combustion chamber. This can be caused by excessive wear of the piston rings or wear involving the valve stem guides and/or seals. Before you condemn what I have mentioned though, I would suggest changing your PCV valve if it has been awhile. If that sucker is plugged, crankcase pressures can be too high and can cause blow-by which can get into your combustion chamber and as a result can foul your spark plugs with oil.
-1992 Ford F-150 (winter truck)
-1998 Lincoln Mark VIII LSC (fun car)