Thomas the Tank Engine & Friends Season 20 Episode 4 Diesel and the Ducklings Episode Title:Diesel and the Ducklings.Episode Description:"Devious" Diesel is known to be mean against the other engines on Sodor, and that is how his diesel friends like it. One day, Thomas spots Diesel being friendly with some ducklings, and threatens to tell everyone whether he is mean or not. Throughout the day, whenever Diesel is about to get devious, by calling Emily names, blocking James' and Gordon's line, and biffing and bashing the Troublesome Trucks very hard in the Shunting Yards, Thomas warns him with a "quack quack quack". As 'Arry and Bert find him suspicious, Thomas shows the ducklings, but the two diesel twins find the ducklings cute and adorable, making Diesel think he can after all be nice.