You probably don’t think about them. You may never have heard of them. But, you can better your car’s warranty its engine has freeze plugs.

Freeze plugs are one of those things you hope never to use since you’ll only use them in a desperate situation. In particular, a freeze plug is used when the antifreeze does what it’s designed not to do – it freezes. And it all comes down to the power of water.

Water carves rivers. Blown up into a typhoon, water can swamp even the biggest ship. Water is sometimes used in manufacturing to cut heavy-gauge steel. Water is powerful. It’s also powerful when it freezes.

This is why we use antifreeze in our cars. Antifreeze is designed to remain in its liquid state even when the temperature outside is precipitously cold. For one thing, with frozen antifreeze, you may have trouble getting the car to start. But, even worse, if the antifreeze in your car’s engine does freeze it’s going to press at its walls.

Have you ever seen what happens when a gallon of milk freezes? The sides of the plastic container bulges out and it usually erupts out of the top. The cap at the top is the weak spot when a gallon of milk freezes. It pops off before the frozen milk cracks the side of the container, though this may still happen.

A freeze plug is a designed weak spot. It’s the cap on a gallon of milk designed to pop out if things start to freeze up inside the engine. In this way, hopefully, the freezing antifreeze won’t crack your engine block.

While a plastic milk jug is beyond inexpensive, an engine block is on the other end of that spectrum. In some cases, a mechanic may be able to weld an engine block. But, often, this is not possible or practicable. The only real solution is to purchase a new engine block. In fact, it may be easiest just to replace the engine in general.

Replacing a cracked engine block is a financial experience that pinches a wallet hard. So, we count on those freeze plugs to pop and reduce the pressure that may crack the engine block. At the same time, it’s also important to make sure your antifreeze is up to snuff. Good antifreeze shouldn’t freeze until a minimum temperature of minus-36-degrees Fahrenheit.

If you have good antifreeze you have less chance that you’ll have to rely on your freeze plugs to save your engine.