Sorry I totally forgot about this - Uhh yeah I remember tyring out the plastic one and it seemed to work just fine .. let me go look and see stuff.
Ok so, I looked and I noticed that it has similar issues, so when I try to do heavy oil cracking, it only seems to have 2 inputs/outputs - so water/steam goes into one input, heavy oil goes into another output, and then it's impossible for anything to happen - where as before there was a definitive output and the product could pass on usually to the other side of one of the inputs. Therefore I could have water/steam go into the side, I could stack them, and a heat source would be at the other side, have heavy oil go into the front, and light oil would come out the back of it.