I got a new pressure washer today and it has a bottle for detergent, which got me thinking about whether plain water is best for an undercarriage wash or if some kind of added agent would help neutralize salt and other corrosive elements. I drive on the beach often so I use a pressure washer with one of those undercarriage washing attachments that rolls under the vehicle. I've just been using straight water from the garden hose. Has anybody here researched undercarriage detergents? I have read that using a citrus based cleaner is a good idea, but I haven't seen any specific product recommendations. Thanks.