Blowing Black Smoke
(I love doing that in my diesel truck!)
Do you happen to have an affinity to one specific brand of diesel engine? I am a Dodge girl so they use a Cummins engine. Chevy uses Duramax and Ford uses Powerstroke. Maybe use one of those? Is that allowed? (I dunno what the naming rules are)
I'm still working on my first cup of coffee so that's about all my brain can function to come up with right now... haha
Do you want the name to have something to do with Diesel or? What are his parents names? I am pretty good at coming up with names for horses based on parents names. Usually in horses you want the name to relate back to the parents so that you know where the horse came from. My friend works on a breeding farm and she always asks me for help

(I know this is a dog not a horse, but still...)