dieseling ONLY occurs in spring powered rifles and pistols. In "adult" air weapons this is how those velocities can be achieved. Too much dieseling will destroy the piston and spring in short order. A controlled dieseling is what you are after, use only a high quality high temp moly grease on the piston skirt, and spring, but use it sparingly. Do not ever use any lube that causes smoke to blow out of the muzzle, or breech when opened. Too much dieseling, too much smoke, and you get too much pressure,and an inconsistent velocity. This is part of why some spring powered weapons seem inaccurate.