Hello,
To start producing oil subproducts you need to meet those requirements:
1) Chemical Template: Advanced Oil Processing is present in material chest
2) Chemical Template: Heavy Oil Cracking is present in material chest
3) Chemical Template: Light Oil Cracking is present in material chest
4) Set filtered cells for Digital Pertorium Gas, Digital Heavy Oil and Digital Light Oil
With that done chest will start making those products which can be used for producing plastic, sulfur and solid fuel (again if you place according chemical templates and set filters for that items)