why can't u use rv antifreeze in a car

[LaCameron]

You cannot use RV antifreeze in a car because the two liquids are engineered for entirely different systems with different materials and operational demands. Using RV antifreeze in a car's cooling system can lead to severe engine damage, including corrosion, overheating, and component failure.

The primary difference lies in the chemical corrosion inhibitors. Modern car engines contain a variety of metals, including aluminum, which is used extensively in engine blocks, cylinder heads, and radiators. Automotive antifreeze is formulated with silicate-based inhibitors specifically designed to protect these aluminum components by forming a protective layer on the metal surface. In contrast, RV antifreeze (the pink or purple liquid used for winterizing plumbing) is typically made from propylene glycol and contains inhibitors meant for the copper, brass, and solder found in residential plumbing systems. These inhibitors are not only ineffective for aluminum but can be corrosive to it.

Furthermore, automotive cooling systems operate under high pressure and extreme temperatures. Automotive antifreeze is designed to withstand these conditions and contains additives to prevent foaming and to lubricate the water pump. RV antifreeze lacks these properties. Using it can lead to pump seal failure and cavitation (the formation of vapor bubbles that implode and damage the impeller). The following table compares key properties:

Property	Automotive Antifreeze (Ethylene Glycol-based)	RV Antifreeze (Propylene Glycol-based)
Primary Use	Engine cooling system protection	Winterizing potable water systems
Corrosion Inhibitors	Silicates, phosphates for aluminum	Benzoates, nitrites for copper/brass
Lubrication	Formulated for water pump seals	Not designed for high-RPM pumps
Heat Transfer	Optimized for high-temperature operation	Lower boiling point, less efficient
Toxicity	Highly toxic (ethylene glycol)	Generally less toxic (propylene glycol)

The result of using the wrong coolant is often not immediate, but a slow, cumulative damage. The lack of proper lubrication will wear out the water pump. The incorrect corrosion inhibitors will allow oxidation and scaling to build up inside the cooling passages, leading to clogged radiators and heater cores, and ultimately, catastrophic engine overheating. Always consult your vehicle's owner's manual and use the type of antifreeze specified by the manufacturer.

[McRebecca]

Think of it like putting diesel fuel in a gasoline engine—they’re just not meant to mix. RV antifreeze is for the water pipes in your camper, not the complex aluminum engine in your car. It doesn't have the right stuff to protect your engine from corroding from the inside out. Using it is a surefire way to end up with a huge repair bill for a new radiator or worse. Stick to the coolant your car's manual recommends.

[StJosie]

It all comes down to chemistry. Car engines, especially modern ones, are full of aluminum parts. The antifreeze for your car has special chemicals, like silicates, that create a protective coating on that aluminum. The pink stuff for RVs has different chemicals meant for copper pipes. If you use the RV kind in your car, it actually attacks the aluminum, causing corrosion that clogs up your radiator and heater core. You might not notice for a few months, but the damage is being done.