This seems easily testable.
Using a full energy cell, produce as much oil as you can. Whether you choose to drain the energy cell or compute the energy-to-fuel ratio is up to you.
Use the produced fuel to power a steam boiler or steam dynamo (more decisive results, since it doesn't have a "warm-up"). Compute the ratio of produced energy to consumed energy. i.e. Energy used in oil fab vs. energy produced from resulting oil->fuel->steam boiler or steam dynamo.
Also, when running at full heat, a 32 HP boiler becomes exponentially more efficient that it is in the warming up phase. I don't know how much more efficient a 32 HP steam boiler is than a steam dynamo for the consumption of fuel, but I suspect that is where you are getting these unprecedented returns.
Also, consider that you could probably sustain 3-4 max sized boilers off of an MFR bio-fuel producer block, running off of 9 items. Energy in FTB is broken, especially so since the release of BigReactors and yellow focused MFR laser drills.