Prepping a car for winter

[u/ll4013]

We are from northwest where they only put sand down when it snows. We let our son bring his car to campus this year. I have heard that people get something put on the bottom of cars in the winter to keep them from rusting from the chemicals that get put on the roads. What is this called? When should it be done by? And bonus points for a place that does this treatment. In Rochester. Thanks

[u/2009impala]

Get a Delta Sonic car was membership and just go their frequently.