Idaho uses 100% salt in liquid brine and solid NACL types and have been for the last 10 years. Being in Boise your vehicle will likely be exposed to less of the product due to its shorter winter season but it’s all the IDT uses.
I live in north Idaho and that amount of surface rust would occur in about a month if driven an average amount. They now salt the roads with either sodium chloride brine via spray or solid rock salt multiple times daily irregardless of weather.
