We always recommend pre-washing for bugs on the bumper, heavy road grime, heavy brake dust, and bird droppings. The blue barrels consist of a high pH liquid and a natural fiber brush that you dip into the liquid and apply to the vehicle. We also have “heated bug sprayers” attached to all the pay kiosks. It looks like a water hose with a sprayer. It’s a high pH liquid that heats up and helps break down dirt on the vehicles. Both items used to pre-wash are safe to use on all vehicles and are Self-serve.