who can tell me what is the cause of oil accumulating beneath the spark plugs in the cylinders. perhaps valves out of adjustment or piston rings allowing blow by? thanks

The valve cover gasket is leaking and the source of the oil. See steps 9, 10, and 11 in this procedure....

http://www.4x4wire.com/forums/showflat.php?Cat=&Number=653021&page=0&view=collapsed&sb=5&o=14&fpart=1