Thank you for the quick response. I should have tried it without the infinity pipe. I see now that the heavy oil is still in the system, because it didn't appear on the tooltip I didn't realise it was still there.

When I disconnect the systems the heavy oil has migrated entirely to the water ...

I disassembled my heavy oil cracking setup and found my tanks of heavy oil had been filled with water instead. I discovered that it was because I deleted an underground pipe connecting to the water system, and because of the way I had my cracking pipes setup this put the water and heavy oil systems ...