It's been a mild winter thus far, but temperatures are dropping in many parts of the country and drivers will likely soon have to deal with sub-freezing temperatures. If you haven't done so yet, this is a great time to look into your car's antifreeze and determine whether it needs to be replaced. Antifreeze is a critical aspect of winter driving, so it's something that every driver should be paying attention to.

Unlike other aspects of a car, there's no hard and fast rule about when to change antifreeze. Most agree that the solution should last for a few years, but it really varies how long the mixture will be good for. Some people change their antifreeze every winter, which is probably not necessary but definitely doesn't hurt. On the other hand, some antifreezes claim to last for 50,000 miles, so it may be a better idea to wait a bit.

A good way to test your antifreeze is by checking its pH level. It's okay if you don't remember how to do that from eight grade science class. Many auto parts stores sell antifreeze test strips that make checking the pH level simple. This will ultimately tell you how long you have to go before changing the antifreeze.

The reason antifreeze needs to be checked is because the chemicals used in the solution are naturally acidic. The idea behind antifreeze is pretty much contained within its name - prevent critical engine parts from freezing up in colder temperatures. To accomplish this, engineers need to use acidic chemicals in order to create a solution that will lower the freezing point of the other vehicle parts. This presented a problem, because acidic chemicals will eat away at the many metal parts in an engine block - especially aluminum. That's why every antifreeze solution includes corrosive inhibitors, which essentially allow the chemicals to function without damaging the other parts of an engine.

The problem with this is that these corrosive inhibitors get used up over time, which leads to the antifreeze getting more and more acidic. If left unchecked, the acidity of the antifreeze can cause major problems for an engine. This is why testing the pH level helps drivers determine about how long they have to go before antifreeze needs replacing.

Once you've determined that your antifreeze needs replacing, the actual process of doing so is pretty simple. Locate the drain valve and empty the antifreeze into a bucket. Make sure you find a place to properly dispose of the solution. Antifreeze has a sweet smell and taste that can attract animals or small children, but it's extremely poisonous. The first thing you should do after draining the antifreeze is find a place to get rid of it - and this does not mean pouring it somewhere discreetly. Find an auto body shop that will accept it or see if your local landfill is authorized to handle it.

Next, it's a good idea to flush out your system. You can buy a special cleaning solution that is mixed with water much like antifreeze is. Close the drain valve and pour this into the system, then let it work for a few minutes. You can then drain it just like you did the antifreeze.

Finally, put together a mixture of about 50 percent antifreeze and 50 percent water (you can give it a bit more antifreeze for especially cold temperatures) and add it where the antifreeze was before. That's likely to last you a few winters, but considering how simple it is to change the antifreeze, it's not a surprise many choose to do it every year.