Too much fuel is deposited when refining crude oil in the small oil refinery.

The vanilla refining ratio is 1 crude oil : 6.67 wood.

If refining 15 crude, or 5 per stack, it deposits 38 wood, when it should be 34 wood (5 * 6.67 = 33.35 or 34).
If refining 900 crude, or 300 per stack, it deposits 2,250 wood, when it should be 2,001 (300 * 6.67 = 2001).

My guess is it's getting hung up that it's 2 decimal places. This isn't an issue for sulfur ore or raw horse meat (1 sulfur ore : 2.5 wood , 1 raw horse meat : 2.6 wood).