There are two groups of car owners: those who've broken down and those who will. It's an inevitability of life that one day you'll turn the ignition key and nothing will happen, or you'll hear a pop and a hiss as your tire does its best impression of a sad hot-air balloon. But you're a person of action, right? A small, affordable kit of items in your trunk will get you going in no time, and it will cost a lot less than a tow truck.
Not a mechanic? Not a problem. Most people aren't. Everything here can be used by anyone, but it doesn't hurt to open the car's owner's manual or look up a how-to video on YouTube. Even if we're not driving much these days, we sometimes do need to head out of the house for essentials, and it can't hurt to be prepared.
To Warn Other Drivers
Traffic Warning Triangle Kit
I used to laugh at the idea of keeping reflective triangles in my car, like it was a suggestion made by lawyers and not real people. Then one day I was driving an old Mustang and its electrical system crapped out. I was in the left-turn lane at an intersection busier than JFK airport, and my emergency flashers didn't work. I couldn't push the 3,400-pound car by myself up the slight hill, and I didn't have a chance of getting it across three busy lanes onto the shoulder. People behind me honked, cursed me out, and threw things because, without flashers on, they couldn't figure out that my car had broken down. Reflective warning triangles placed on the road behind me would've clued them in to just drive around.
To Raise the Car
Strongway 4-Ton Hydraulic Bottle Jack
Bottle jacks are compact, and this one is more than strong enough to lift a heavy SUV or van for a tire change. If your car came with a jack, replace it with this one. Don't ever go underneath the car when it's supported only by a jack and not separate jack stands. You shouldn't be under there to change a tire anyway, and jacks do fail, even good ones. Jack the car up on the thick-looking parts of the frame underneath, not bodywork. There will be images in your owner's manual of the best jacking points.
To Replace Tires
Performance Tool 4-Way Folding Lug Wrench
There are no separate parts to lose when you're using the classic X-shaped lug wrench. If your car has a spare tire, you'll need one of these to swap it with your flat. This one folds so it takes up less space in your trunk and has four sockets sized for the most common lug nuts: 17 mm, 19 mm, 21 mm, and 23 mm, which are roughly and respectively equal to 11/16 inches, 3/4 inches, 13/16 inches, and 7/8 inches.
To Repair a Flat
Fix-a-Flat Tire Sealant
If your car doesn't have a spare tire—more common now than ever—you can use an aerosol product such as Fix-a-Flat. You connect the can to the punctured tire's valve stem. The sealant is sprayed onto the inside of the tire to patch the hole and then reinflate the tire. Don't expect the tire to be as good as new. This is meant to get you to the nearest mechanic so you can have them repair it or replace the tire.
To Check Your Air Pressure
Milton S-921 Pencil Tire Gauge
Whether or not you drive a lot, you car's tires will lose about 1 pound per square inch of air pressure each month. Driving on tires with underfilled worsens your fuel economy, braking, handling, and tire life. But that'll also happen if you fill them too much. Check the air pressure of each tire with a gauge at least once a month, and use it when refilling your tires at a gas station's air pump. Your tire pressure will be listed in the owner's manual and on a sticker (most likely) in the driver's doorjamb, assuming you're using the tires recommended by the manufacturer. Check your tire pressure every time your car comes out of the shop, too.
To Jump-Start Your Car
Husky 20 ft. 4-ga Jumper Cables
If your car battery dies, you can jumpstart it by connecting it to another car, which will at least get you to a store to buy a replacement (if you don't turn the car off again). Large, four-gauge wires let power flow more easily, like using a thicker straw in a milkshake. Look up the proper procedure on how to connect the cables (ideally before you get stuck on the road, but you can always look it up on your phone). If you do it wrong, you could electrocute yourself. I can't tell you how many times I've seen spark showers from people who screw it up.
To Refill Your Coolant
Prestone 50/50 Antifreeze
Cars burn through coolant (aka antifreeze), and you should check your coolant level often. If it's low and you drive off anyway, you could ruin the engine. Carry a spare gallon so you can top it off wherever you are. Green-dyed antifreeze can be added to any antifreeze you already have in your car's cooling system. Get the premixed coolant that says "50/50" on it, otherwise you're going to have to find a bucket and a gallon of distilled water on the side of the road if you mistakenly buy the concentrated bottle.
To Top-Off Your Engine Oil
Valvoline Advanced Full Synthetic 5W-30 Engine Oil
Check your engine oil level occasionally. If it's low, you need to top it off immediately, before your engine destroys itself. Look in your car's owner's manual to see the recommended oil designation (10W-30, 10W-40, etc.), and buy a quart of that. But if you can't find your manual, 5W-30 is a good general oil that'll work for most engines and in most situations. Likewise, go for full synthetic rather than synthetic blends or conventional mineral oil. Keep a roll of paper towels, too, so you can wipe off the dipstick before measuring. Remember to measure and add oil after the engine has warmed up completely and to turn off your engine when you're doing it. Adding too much can be as bad as too little.
To See in the Dark
Maglite Mini PRO LED AA Flashlight
You're not always going to break down where there's light. Maglite flashlights are tough enough to survive your trunk and the inevitable drop onto the pavement, and you can remove their heads to turn them into mini lanterns if you have your hands full and need to set it down while you work.