Heat and cold attack a vehicle differently. Heat degrades battery chemistry, coolant, and rubber. Cold thickens oil, weakens batteries, and lowers tire pressure. Road salt then adds a conductive film that keeps metal wet at temperatures where it would otherwise stay dry.
Is road salt or cold worse for my car in winter?
Steel rusts when iron meets oxygen and water. Dissolved salt makes that water conductive andaccelerates the reaction sharply, and it also lowers the freezing point so the underside of thecar stays wet at temperatures where it would otherwise be dry. Damage concentrates in wheelarches, rocker panels with blocked drain holes, steel brake lines, and any stone chip that hasexposed bare metal.
Rinsing the underbody every week or two through the salting season is the single mosteffective defense, and it matters more rather than less if the car lives in a heated garage,because a warm damp car corrodes faster than a frozen one.
Impact of Extreme Weather on Your Vehicle: Questions
What is the biggest impact of extreme weather on your vehicle?
In New York, the biggest impact of extreme weather on your vehicle is road salt, which keeps metal wet and drives rust, while heat and cold mainly attack the battery, fluids and rubber.
Why does my tire pressure warning come on in winter?
Cold air contracts, so tire pressure drops as temperatures fall. Check and adjust the pressures when the weather turns.
Does summer heat hurt batteries?
Yes. Heat speeds up the chemical wear inside a battery, which often shows up as a failure the following winter.

