Well you can use thinner.. but disposing of it and also disposal of the Zep solvent is going to be your issue. Hence why i just used brake clean as it evaps.
So check around ither shops and see how much for disposal when your ready to change the solvent. Shops usually have some company to pick it up and recycle it. If you get on the same page with them, they might let you pay them for disposal.
^^^ This.
I have a parts washer...well used to anyway. Gave it to my buddy that lives a few roads over from me when I started working at the place I am now. We have a huge hot tank at work so I don't need the washer anymore. If I need to at home, I can always run over to my buddies as I have the code to the shop.
The fluid in the parts washer is a solvent based fluid that comes in a big drum that the cleaning tank sits on.
It was always a problem to find out where to dispose of the old cleaner in the tank. My buddy and I finally got in good with a local shop owner here. Gave him some money for his time and dumped into his outside tank. He has a company come and dispose of the old oil, coolant, oil filters, and solvent tank gunk.