It won't come as a surprise that most automotive chemicals, even fresh off the shelf, are pretty poisonous. They also tend to be flammable and corrosive—and the time they spend at work in your car doesn't improve them. Oil, coolant, brake fluid, and battery acid all are chemicals a do-it-yourself mechanic might find the need to get rid of.
Proper disposal is part of doing the job right. Here are some suggestions on how to handle automotive waste.
Don't mix materials. For example, don't put brake fluid in the same container as motor oil. Mixing can make recycling impossible.
Put liquids in sealable, un-breakable containers and label them clearly.
Don't store containers of waste in the sun. In fact, don't store them at all if you can help it; get them to a recycling collection point right away.
See if a nearby service station or auto supply store accepts old motor oil, transmission fluid, and other waste. You can also get information on where to dispose of most of these things from your health department, environmental protection office, garbage company, and, in many areas, the Internet.
When you buy chemicals such as brake fluid and oil, get only what you need at the moment. Once their containers are opened, they don't age gracefully. And buying them in quantity may create an extra disposal problem.
Read labels and follow directions.
Oil — According to the EPA, used motor oil is a major source of oil contamination of waterways and can result in pollution of drinking water sources. It isn't legal to pour oil down the drain or put it in the garbage; take it to a collection facility for recycling.
Batteries — The main ingredients in car batteries are lead and sulfuric acid. The best way to handle battery replacement is to have a shop do it. If you do replace it yourself, once you've removed the old battery, store it upright in a container that's resistant to acid. Dumping a car battery in the garbage is illegal; take it to a recycling facility. Batteries vary in life expectancy; buying the longest-lived battery you can find probably will mean a higher initial price but it will reduce the need for replacement.
Coolant — Most coolant is sweet and looks festive and tasty because of its bright color (usually green). These qualities can make it attractive to children—and pets love it. However, it's made of ethylene glycol, a poison. Some coolant uses propylene glycol instead and is less toxic. But no one is going to benefit from drinking even the most benign antifreeze, so be sure you keep containers of it out of harm's way. Take used coolant to a hazardous waste collection site.
Gasoline — Even though gasoline is both poisonous and explosive, people store cans of it in their garages and cellars. If you're among them, use a container designed for gasoline storage and keep it away from possible ignition sources, such as a water heater pilot light or direct sunlight. Gasoline evaporates rapidly and the vapor is explosive, so it's best not to use it for such Heloise-esque things as taking gravy stains off a tie.
Freon — In the early 1990s, car makers switched from using chlorofluorocarbons (CFCs), like Freon, in air conditioners because of the harm they cause the earth's ozone layer. Although it may be possible to retrofit older car air conditioners to use a more benign CFC substitute, it probably would not be cost-effective. CFCs are controlled substances these days; if you have an older car, when the AC goes out, have a licensed shop fix it. To keep the seals from drying out, run the air conditioner periodically (once a month is often enough) even if the weather is cool.
Transmission fluid — It's corrosive and will burn. Take it to a hazardous waste collection facility.
AAA handles battery replacement and disposal of old batteries with its AAA Mobile Battery Service.
This article was first published in November 2001 and updated in March 2019. Some facts may have aged gracelessly. Please call ahead to verify information.