On big engines in the oilfield, we used inverted injectors with either Marvel Mystery oil or water. In the winter time, we didn't want to chance the water freezing. These were used all the time to keep an engine clean and worked very well. Back in the 70's in the Oklahoma oilfields, one could obtain "drip" gas from well heads in wintertime (just condensate from the gas and oil). This stuff would run your car, but it stunk and had horrible octane. The solution was to mix with gas, or inject water to slow the burning (like the navy planes do). There was a kit you could buy with a one gallon jar on the fender and a vacuum line from the top to the intake manifold. Another line from the lid to below liquid level caused the water to vaporize and bubble and some mist was going into the engine.

Upon inspection of a 235 six cylinder, the pistons looked brand new after many miles - amazing stuff. I don't have any idea what it did to the oil, but I think it was just like running an engine in the rain (100% humidity).