My just owned 2005 Tacoma has a layer of sand all over the undercarriage and wheel wells. Its really thin layer..dry and struck to metal surface and wont come off. There is some loose sand as well. The Rust proofing guy said that some people take it purposely on sand and dirt after rust-coat to get a protective layer on the frame. Anyone heard of this phenomenon...???
My real question is ..Is it a good idea to (pressure)under wash to get all loose sand out and then rust-coat. Thanks.