The big oil leak controversy started when Kawasaki changed valve cover gasket materials. I believe that the old one had asbestos in it, worked perfectly, but not acceptable to the EPA. The first one that replaced it was red in color, seemed to seal adequately, but was a real pain to get off. The second version is the one still in use (p/n 11060-1691) now superseded to 11061-1121, which is graphite material laid on a steel gasket. It's a minor pain to remove (steel toothbrush mainly), but not as horrible as the red one. When replacing the gasket, always replace the cam end plugs. The procedure that has worked the best for me is: #1) clean the gasket surface of all debris (head and valve cover). #2) clean the cam plug area and bolt holes in the cylinder head with a tap to remove old sealant. #3) clean the threads on the four end bolts of any old sealant. #4) clean the bolts, new cam plugs, valve cover and head in the area around the end plugs with acetone/contact cleaner/mek. #5) apply either the Right Stuff sealer or Three Bond 1207 (available at Toyota dealers or Suzuki dealers) to the cam plugs total circumference and about 1 inch either side on the cylinder head. #6) Lay the gasket into place, and put sealant on top of the gasket the same width as the sealant on the head next to the cam plugs. If you are planning on running a long time between valve adjustments, put some sealant under the bolt heads (cam plug bolts). #7) Torque the valve cover bolts to 8 ft/lbs, starting in the center, working outward. If possible, let the sealer set overnight, peel off excess when dry. If this procedure is followed, the minimum mileage before leakage will be 5K miles to a high of 20k miles. Re: sealant; the Right stuff seems to vary in quality, where as the 1207 is consistent. If the unit needs to be back in service ASAP, the Right Stuff works the best. The Right stuff doesn't seem to set up if you are in a low humidity area. When the Santa Ana winds are blowing here, I've had to use a water spray bottle on the sealer after installation to get it to set up. If possible, use the OEM parts for this operation; the aftermarket stuff doesn't seem to work as well (although it's substantially cheaper).