The pump itself fits the 20 liter W3-oil bucket perfectly. It is fairly easy to install. Just make sure you pull the "neck" out of the bucket for screwing the pump on first and then push the neck with the pump base down (don't push down on the top of the pump, as it will actually pump oil right away ) back into its place. The pump dispenser/spout could be at least 2 inches longer, so the oil can flow directly into the feed bucket without having to lift and tilt the bucket to avoid spillage. We attached an extension to help with the above and it works good. However, we usually have oil "stuck" in the extension, which comes out when we flick it. There is always "after leakage" after each use. Unless you use a "drip catcher" on the spout, or a can under the spout, you will have spillage on t...