The Rear End Spreader can rub.
Many put slippery things on it, most say the horse will callous up after a few days.
The Armor All Original Protectant will make the plastic very slippery.
It would be the best product to use if slipperiness is what you are looking for.
I would recommend the liquid and not the wipes or gel.
Again, thank you for contacting us.
It is available in a one gallon refill jug, however, it usually has to be specially ordered. I would check with Autozone, Napa, or other auto supply store.