The key to using Mineral Spirits is to use it as an initial flush to get most of the oil out of the system. Then blow it out THOROUGHLY and flush that out with a/c flush or Brake Cleaner.

I personally CAN NOT use Acetone. When in the Army we used some really nasty chemicals to clean electric connectors and such. At that time my sinuses developed a sensitivity that is triggered by some chemicals. Acetone is the worst of them. If I'm even in the same room with open Acetone I stand a REALLY GOOD chance of developing sinus swelling that results in a headache that feels like I have an ice pick stuck behind my eyeball.

If you use the regular a/c flush wisely witih a rubber tipped flush gun, it will go a long way, making it more affordable.

My $0.02,