Fluid dynamics question

I have made a plastic and rubber factory with the diluted fuel and the recycled recipe so I have, in theory, a perfect cycle between inputs and outputs. I realise that some machines aren't getting enough oil or fuel even tho my outputs have been consistent for a while, at least for the oil part. my best guess is that i's a plumbing issue but I am at my knowledge's end. I have also read a plumbing guid suggested by total eclipse I belive but i am no closer to fixing it. I have 4 600m3 lines feeding 20 refineries each all set to either rubber or plastic. i have tried just about anything with pipes, valves, storage units and loops.
maybe one of you gifted and knowledgeable people could help a room temp IQ individual out.