It is, DO NOT use Wd40 on the O-rings. And you should never pack any grease in the bearings, the fuel is the lubricant. If you really want to clean the motor internals, take it apart and clean it with nitro cleaner or alcohol. You can clean and scrub the case with simple green and a brush. You can rinse it off with water after you scrub it, but as soon as your done run some fuel and or afterun oil all over the inside. If the oring on the backplate is good, just put a few drops of oil on it and seal it up, you really dont need any sealer on it.