Have you tried math?
Take a purchase price of let's say €500000 at 6%, that's €30000
Now add 3% insurance, that's €15000
Total €45000, at 300 hours per year you have €150/hour.
About 250 Liters of that good liquid sets you back another €350, for a total of €500.
You still need to buy parts, oil, pay the mechanics and store the machine.