TL;DR
To reduce confusion for new players, the oil refinery should only show input and output pipes that are used for the specific recipe.What and why?
Many new players that see the oil refinery for the first time get confused by the amount of pipes that go in and out of the refinery.A common mistake is that they connect the wrong inputs and outputs, thinking they all accept oil and output petroleum.
Similar to how assembly machines only show the pipe interface when a relevant recipe is chosen, the oil refinery should only show the extra pipes when the advanced oil recipe is selected, and hide the unused pipes when the basic oil recipe is selected.
The change is cosmetic, but could help new players understand this building better.