I kept thinking about the heated fluid idea so I stopped by the local PetsMart on my way home from work and picked up a submersible aquarium heater for about $25 (the ones for reptile tanks that can be fully underwater and not hanging on the side of the tank). Well it turns out that is the trick. Just heat up the fluid and it improves the chemical reaction immensely. Here is a spot by the front leaf spring hanger. I aimed the sprayer and let it go for about two minutes to check the aim while I got the camera ready and in that time it already converted most of the surface rust to clean metal.
