OSPHO rust preventative and coal stoves

The local hardware store carries a product called OSPHO, said to stop rust. Basically the info says it converts iron oxide to iron phosphate.
I do the baking soda routine for end of season shut down but am wondering if this product might work better. Even after the baking soda, it seems there is some accumulation of rust during the summer, I keep a light in the stove to keep it dry.

Any thoughts.

I've used Ospho for decades on auto restoration applications. It's a great product but in my opinion not for use on stoves. OSPHO is a balanced formula of Phosphoric acid, Sodium Dichromate according to the web site. (http://www.ospho.com/data.htm) The MSDS says it's 75% phosphoric acid. It does make a hard surface (iron phosphate) that takes most oil based paints well. It's great because you don't need to get all the old rust off before you paint the rusted metal. Future rust resistance comes from the paint you apply on the converted rust surface. But in a stove application you are not going to paint it, at least not with anything that will stand the heat of a coal fire.