Gotta ask have you been in school in the past 20 years?
I'm not sure if any state school has lessons divided by gender aside from P.E. and possibly some Sex Ed lessons...
Gender division in schooling was certainly a thing in the 70's and probably the 80's.
Silly one, and but do tanks run on diesel?
Every other heavy machine I can think of typically uses diesel for their engines: tractors, lorries, boats.
Also diesel is less flammable then petrol or hydrogen in the event of a spill of leak...