Check your own tires and oil in five minutes flat

Quick answer: For tires, use the pressure printed on the sticker inside the driver's door, not the number on the tire, and check them cold. For oil, park on level ground, wait a few minutes with the engine off, wipe the dipstick, dip it again, and you want the oil between the two marks.

It's 7:40 on the first really cold morning in January. You're halfway to school in your mom's sedan when a little orange light shaped like a horseshoe with an exclamation point inside it pops up on the dash. Your stomach drops.

Breathe. That's the tire pressure light, and on a cold morning it's one of the most common lights a car ever shows you. Air shrinks when it gets cold, roughly one PSI for every ten degrees the temperature drops. A tire that was fine last week at 60 degrees can be three or four pounds low at 25.

You can fix that yourself at the next gas station in about five minutes. You can check the oil in about three. Neither job takes strength or special skill. They take a gauge that costs less than lunch and a willingness to get one finger a little dirty.

Be honest about "before you drive anywhere"

You don't need to pop the hood every time you go to practice. Nobody does that, and if somebody tells you they do, they're exaggerating. The routine that actually works looks like this:

• Every time you drive: walk around the car before you get in. Look at each tire. Ten seconds. If one looks flatter than the others, it is.
• Once a month and before any long drive: put a gauge on all four tires and check the oil.
• Any time a warning light comes on: deal with it that day, not "this weekend."

That walk-around matters more than it sounds. A nail in a tire usually shows up as a slow leak first, and slow leaks are the ones you catch by looking.

The tire number almost everybody gets wrong

Look at the side of your tire and you'll find something like "MAX PRESS 44 PSI." That's the most the tire can safely hold. It's NOT what you should fill it to.

The number you want is on a sticker inside the driver's door frame. Open the door and look at the edge where it closes. Some cars put it inside the gas door or the glove box instead, and it's always in the owner's manual. On most passenger cars it lands somewhere in the 30s. Front and rear can be different, so read the whole sticker.

Check the tires when they're cold. That means before you've driven, or after the car has sat for about three hours. Driving warms the air inside and makes the reading come out high. If you just came off the highway and a tire reads a pound or two over the sticker, leave it alone. Top up anything that's actually low, then check again in the morning.

Doing the tires, step by step

1. Park close enough to the air machine that the hose reaches all four tires. Turn the engine off.
2. Unscrew the little cap on the tire's valve stem. Put it in your pocket, not on the ground. Valve caps roll, and they roll straight toward drains.
3. Press the gauge straight and firm onto the valve. A quick hiss is normal. A long hiss means you're on crooked, so push straighter.
4. Read the number and compare it to the door sticker.
5. If it's low, start the machine (coins or a card, usually a couple of dollars), press the hose nozzle onto the valve and add air in short bursts of a few seconds. Check again with your own gauge. Many machines let you set a number and beep when you hit it, but those machines get dropped and run over all day, so trust the gauge in your hand.
6. If you overshoot, press the tiny pin in the center of the valve with the back of the gauge or a fingernail. Little bursts.
7. Cap back on. Next tire.

While you're crouched down anyway, do the penny test. Put a penny into the tread with Lincoln's head upside down. If you can see the top of his head, the tread is worn thin and the tire needs replacing soon. Tell whoever handles the car.

The annoying part nobody mentions: sometimes the air machine is broken, or the hose won't reach the far side and you have to pull the car around. That's normal. It's not you.

Checking the oil

Park on level ground and turn the engine off. If you've been driving, wait five to ten minutes so the oil drains back down where you can measure it. Your owner's manual may say something slightly different, and the manual wins.

Pop the hood with the lever near your left knee by the driver's seat. Then go to the front of the car and feel under the middle of the hood's front edge for a second latch. It's usually a little tab you push sideways. Lift the hood and use the prop rod, unless your hood stays up on its own.

The dipstick is almost always a bright yellow or orange loop handle. Then:

• Pull it all the way out and wipe it clean with a paper towel.
• Push it all the way back in.
• Pull it out again and look at the tip.

You'll see two marks. They might be dots, holes, lines or a crosshatched patch, sometimes labeled L and H or MIN and MAX. If the oil sits between them, you're fine. If it's at or below the low mark, it needs oil. On most cars the gap between low and full is about one quart.

Check the color too. Fresh oil looks like honey. Dark brown is normal as it ages. Black and gritty means it's overdue for a change. And if it looks milky, like chocolate milk, don't drive the car. Call a parent and get it to a mechanic.

If you need to add oil

The right type is listed in the owner's manual and often printed right on the oil cap, something like 0W-20. Use that one. The cap is on top of the engine, marked with a little oil can symbol.

Don't open the wrong cap. The coolant cap should never be opened on a hot engine, and the windshield washer reservoir won't do you any good here.

Pour in about half a quart, wait a minute, and check the dipstick again. Sneak up on the full mark. Too much oil causes its own problems, and you can't easily pour it back out.

Some newer cars don't have a dipstick at all and show the oil level in a menu on the dash. Annoying the first time, easy after that. The manual shows you where.

One more thing. A red oil can light that comes on while you're driving isn't "a little low." It means oil pressure. Pull over somewhere safe, turn the engine off and call home.

What lives in your trunk

• A tire gauge. A digital one costs under fifteen dollars, and a basic pencil gauge works fine too.
• A roll of paper towels.
• One quart of the oil your car takes.
• Disposable gloves, if you'd rather not get your hands dirty.

What to skip: kicking the tire and calling it checked. Modern tires can be badly underinflated and still look completely normal. Only a gauge knows.

Doing it yourself is the whole point

At a gas station, somebody you don't know might wander over and offer to do it for you. Most people mean well. You can still say "Thanks, I've got it" and keep going. That's a full sentence and you don't owe anyone more. If anybody makes you uneasy, get back in the car, lock the doors, drive somewhere busy and call a parent. It's the same instinct as writing down your standards before anyone tests them. You've decided ahead of time, so you don't have to figure it out on the spot.

It helps at the oil change shop too. When you know what your oil looked like last week, you're a lot harder to talk into extras you don't need. You walked in already knowing what's what.

The first time, ask your mom or dad to come out to the driveway with you. Ask them to stand there while you do it, not to do it for you. Ten minutes, and it's yours for life.

Then the next time you borrow the family car, bring it back with a full tank and all four tires sitting right on the sticker number. Your mom will notice. She probably won't say anything for a while. Then one day she'll hand you the keys before you've even asked.