He knows which side the gas cap is on without looking

Every Saturday morning, Dan walks a slow lap around my SUV with a coffee in one hand and a tire gauge in the other, the way some men walk a vegetable garden. The first time I saw it, I asked what he was looking for.

"Nothing," he said. "That's the goal."

We've been married eleven years. In that time I've driven something like a hundred thousand miles and understood about forty of them. These are the things he knows. I'm catching up.

The little arrow on the gas gauge

For years I'd pull into a station, pick a pump, and learn I'd guessed wrong only after I was stretching the hose across the back bumper like I was trying to lasso a calf. Then on a road trip in a rental, I got out and walked around the whole car. Twice. Dan leaned across the seat and tapped the dashboard.

There's a tiny triangle next to the fuel pump icon. It points to the side the gas door is on. It's been there my entire driving life.

What he's right about: Glance at the arrow before you pull in, especially in a rental or a borrowed car. And when you borrow a car, bring it back with a full tank, even if it came to you on fumes. That's his rule, and I've watched it make him the most trusted borrower in our family.

The pressure number isn't on the tire

When the tire light came on, I did the responsible thing. I read the big number molded into the sidewall and filled all four tires to it. The car rode like a shopping cart on cobblestones. Dan let some air back out and walked me around to the driver's door.

What he's right about: The correct pressure for your car is on the sticker inside the driver's door jamb. The number on the tire is the maximum the tire can hold, not what your car wants. Check about once a month, with the tires cold, before you've driven anywhere. Pressure drops when the weather turns cold, which is why that light loves the first freezing morning of the year. Keep a gauge in the glove box. Gas station gauges have been through a lot.

A penny is a tread gauge

I thought tires were finished when they went flat. Dan thinks they're finished well before that, and he proved it with a penny from the cup holder.

What he's right about: Slide a penny into a tread groove with Lincoln's head upside down and facing you. If you can see the top of his head, you're down to about 2/32 of an inch, and it's time for new tires. Check a few spots on every tire. If one edge is wearing faster than the other, that's usually alignment or pressure, and it's worth having a shop look.

Dashboard lights come in colors for a reason

My old approach to every warning light was the same: brief panic, followed by a firm decision to look into it later. Once the check engine light came on and I announced it was "probably the gas cap." It was the gas cap. I was unbearable for a week.

It isn't always the gas cap.

What he's right about: Yellow or amber means get it checked soon. Red means pull over somewhere safe, now. A steady check engine light can be minor, so tighten the gas cap until it clicks and give it a few drives. A flashing check engine light usually means the engine is misfiring. Ease off and get to a shop right away, because driving on it can wreck expensive parts. A red oil pressure or temperature light means stop and shut the engine off. Many auto parts stores will read the code for free so you walk into the shop knowing what you're dealing with.

The windshield sticker isn't the law

I treated the oil change sticker like a court order. Three thousand miles to the day. Dan asked if I'd ever opened the owner's manual. I said I'd opened the glove box and seen it in there, which felt close.

What he's right about: Your owner's manual sets the oil change interval, and on plenty of newer cars running synthetic oil it's well past 3,000 miles. Many cars also have an oil-life monitor on the dash. Short trips, towing, dust and extreme heat often count as "severe service" in the manual, which shortens the interval, so read that part honestly. Check the dipstick once a month, parked on level ground with the engine off and cooled. And when the shop hands you a list of extras, "Just the oil change today, thanks" is a complete sentence. If saying no feels hard, it's the same muscle as negotiating an offer when you've never done it before.

Jumper cables go on in an order

The first time I tried to help, I held both clamps in one hand like a bridal bouquet. Dan very calmly took them from me.

What he's right about: This one isn't a joke. Batteries can give off explosive gas, and clamps that touch each other spark. Check your owner's manual first, because some cars have specific jump points. The usual order:

• Red clamp on the dead battery's positive (+).
• Other red clamp on the good battery's positive (+).
• Black clamp on the good battery's negative (−).
• Last black clamp on bare, unpainted metal on the dead car's engine, away from the battery.

Start the good car, let it run a few minutes, then try the dead one. Remove the clamps in reverse order. A portable jump starter in the trunk means you don't need a second car or a stranger.

The spare tire needs air too

I got a flat on the way to a birthday party with a sheet cake in the back seat. I opened the trunk, found the spare, and discovered it was also flat. It had been flat, Dan estimates, since the previous administration of our household, which is to say before we bought the car.

What he's right about: Check the spare when you check the other four. The right pressure is on the spare itself or in the manual, and compact spares often need much more than your regular tires. Know where the jack and lug wrench live before you need them. If you change a tire yourself:

• Level ground, parking brake on, hazards on.
• Loosen the lug nuts slightly before you jack the car up.
• Jack only at the lift point shown in the manual.
• Never put any part of your body under a car held up by a jack. Ever.

A compact "donut" spare is for getting to a tire shop, not for living on. It has a speed and distance limit printed on it, so read it and obey it. Recheck the lug nuts after a short drive. If you're on a narrow shoulder with traffic flying by, call roadside help. No tire is worth standing next to a highway.

Never open a hot radiator

Our old minivan overheated in a grocery store parking lot. Steam was rolling out from under the hood, and I reached for the radiator cap because that's where the problem obviously lived. Dan said my name in a voice I've heard maybe twice. I stopped.

What he's right about: The cooling system is under pressure when it's hot, and opening the cap can spray scalding coolant at your face. Pull over, turn the engine off, and wait until it's completely cool, at least half an hour and longer is better. Check the coolant level at the overflow reservoir, between the marked lines, and only when it's cold. If the temperature gauge starts climbing in traffic, turn off the A/C and run the heater on full to pull heat away from the engine until you can stop. If it keeps overheating, it needs a mechanic, not more coolant.

What I'm learning

Last month the tire light came on during a cold snap. I read the door sticker, filled all four tires before I'd driven anywhere, and didn't mention it to anyone. Dan noticed anyway, because of course he did. Saturday lap.

He didn't say a word. The next morning there was a second tire gauge in my glove box.

I married a man who lies on a freezing driveway so I don't break down on the way to school pickup, and I've come to think that's exactly what you judge a man by. I still couldn't pick a catalytic converter out of a lineup. But I know which side the gas cap is on.