i could program the code you need for your problem. But you also need a little bit more electronic components, especially for the oil temperature control. I think a PTC or NTC would help u by solving your problem.
Theres only one thing i need from u.....Could u make a chart of the system, a photo of the Stepper u want to use and post it to this thread? I would program it for 0€ because it´s my hobby...
Greetings from Germany and maybe we will see us in Venlo