It is used instead of the water based cleaner. Kerosene is relatively inexpensive compared to other commercial cleaners, and the ones that I have used were mostly kerosene anyway. Trans fluid is also a grease cutter and a lubricant. I have used trans fluid in my fuel tank for years as an injector cleaner and lubricant. Was told about this by a GM mechanic after the dealership service department told me I would need all my injectors replace. A couple quarts in the fuel, and drive it for a week and the problem went away. I would do a mix in the parts washer of 1 qt trans fluid to 1 gallon of kerosene.