Diesel Generator is part of the GregTech mod which produces energy when operated. The Generator will run on different kinds of fuel and has a maximum output of 12 EU/t. The Diesel Generator works best with Fuel. Oil can be easily refined with the Refinery. Other fuels can be produced with much more complicated machinery and processes, like the Distillation Tower and Chemical Reactor.
Comparing the Diesel Generator to other oil-operated generators:
The Diesel Generator scales better than the Steam Boiler and does not require time to heat.
The Diesel Generator outputs EU, unlike the Combustion Engine and also does not require cooling.
The Diesel Generator can not be switched off instantly
An array of Diesel Generators needs 2 Routers instead of waterproofed pipes
Although the Diesel Generator allows for easy generation of IndustrialCraft2 power from Fuel or Biofuel, this comes at a thorough loss to efficiency. A bucket of Biofuel will produce only 32,000 EU in a Diesel Generator, whereas other methods of conversion (requiring more infrastructure, but allowing for far greater efficiency) allow for 250,000 or 500,000 EU to be generated per bucket.
If one is able to utilize the Power Converters mod, a bucket of Biofuel will generate 200,000 MJ in aCombustion Engine which can then be converted into EU at a 2:5 ratio, resulting in 500,000 EU. The same ratio can also be achieved by sending power to a Magma Crucible filled with Netherrack (can also be filled with Cobblestone for a fully automated system at a cost of 50% efficiency) and sending the resulting Lava to a Thermal Generator. However, these methods require setup and can come at a higher cost, whereas the Diesel Generator is relatively inexpensive and easy to setup and generate power from.
The OmniWrench only works on the bottom or top face of this machine; presumably this is a bug.
Note that the diesel generator DOES NOT burn diesel canisters obtained by distilling crude oil/oil sand in the Distillation Tower from Traincraft