Seating the oil cap gasket
Yesterday I needed top off the oil and found that when removing the cap, the gasket decided to come out of its seat in the cap. This bugged me mostly because of the problems that develop when the gasket is not seated correctly. After trying to work the circular gasket back into its "U" shaped channel in the cap with no success I found the following procedure works pretty well.
Work just the inside edge of the gasket into the channel leaving the outside edge floating above the outside edge of the channel it needs to seat into. Put the cap carefully back on the valve cover and tighten slowly. This should seat the outside edge pf the gasket into the channel. Then take the cap back off and inspect to make sure it seated correctly. If seated correctly, put the cap back on and check for leaks after driving a few miles just to be sure. A little film of oil on the gasket is always a good idea since you are probably going to clean the top of valve cover before you put the cap back on.