I have a pair of Tin Haul's I have been wearing for three years give or take a month. They have never been wet or muddy I have always use them as my work shoes. I teach high school. They have started to squeak really bad when I walk. What causes this and what can I do to get rid of the noise? I really like them and want to wear them. 

I have tried to put power in then and on them have though about trying WD40 but didn't want grease spots on my boots.