I tried to add Natural Gas from the Magneticraft mod into the gas turbine, but it won't accept it, despite it being obvious that it should be accepted and be burnt just like a normal real life gas turbine. So adding compatibility for liquid fuels from other tech mods would be very versatile in a modpack... Also i noticed that the Gas turbine doesn't fully empty the input tank once the fuel is removed, and always stops at like 50 mb of fuel and won't accept another compatible fuel because of that. The only work-around is to break the gas turbine and form it again.

If you want Natural Gas you will need to use CraftTweaker. We can't account for every mod out there that has a "gas". As for the input tank, the reason for this is the recipe amounts, vs, the tank size. We give it a size and whatever fluid is used may have different usage values.

What's the zenscript for that?

It's on the curseforge page.

Also you forgot about the issue of the gas turbine not emptying the fuel to zero and instead keeps it in the tank

It could easily be done with a few lines of code, so that if the liquid level is lower than the burnrate per tick, then make it zero (or null) without creating fuel byproducts. That way you can switch the fuel around

But I did "As for the input tank, the reason for this is the recipe amounts, vs, the tank size. We give it a size and whatever fluid is used may have different usage values."