.. I think the primary difference is acetone penetrates deep and carries the oil with it, then evaporates leaving the oil where it would not go on its own. I've used it more on rusty nuts and bolts than engine interiors, but it works great for getting oil into any tight place. From ddavidv's description, I don't think he has enough rust to need to remove the head at this point. If the rings happen to be stuck, the mixture might be helpful. ..