the Maraxis planet mod adds a diesel fuel type for its submarines and makes barrels of light oil and petroleum work for that type. would you be able to make your diesel engine work with that fuel type?

There would be balance problems if I make them compatible. Diesel fuel has no bonuses, since the power and speed bonus is included in the base stats of the diesel engine. Oil barrels, on the other hand, have bonuses similar to rocket fuel. If I make them both usable as fuel, then barrels would be overpowered or diesel fuel would be underpowered.

While I could try to rebalance them, I don't see that it would yield a significant benefit to gameplay.