Changing your own oil without making a mess of it

Two mistakes account for almost every oil change that ends badly. The first is the double gasket: the old filter's rubber ring stays stuck to the engine, you screw the new one on top of it, and about ninety seconds after startup your oil is on the ground and your bearings are doing something expensive. The second is a drain plug torqued down like a lug nut into an aluminum pan, which strips the threads and turns a forty-dollar job into a pan replacement.

Both take three seconds to avoid. Wipe the filter mount with your finger and confirm it's bare metal. Use a torque wrench on the plug.

Everything else is straightforward, and you can do the whole thing in half an hour once you've done it twice.

Get the numbers before you buy anything

Open the owner's manual, or find the service section of your car's forum. You want four things.

• Oil viscosity. 0W-20, 5W-30, whatever it says. Modern engines are built tight around a specific grade. This isn't a suggestion.
• Capacity with filter change. Usually between four and eight quarts. Write it down.
• Filter part number. Every filter brand publishes a cross-reference.
• Drain plug torque. Often somewhere in the 20 to 30 lb-ft neighborhood on a steel pan, lower on aluminum. Use the number your manual gives, not the neighborhood.

Buy the oil, the filter, and a new crush washer. That last one is the part people skip. It's the soft aluminum or copper ring on the drain plug, it's designed to deform once, and reusing it for the fourth time is why your driveway has a spot. Many filters ship with one in the box. If yours didn't, they're about a dollar.

Synthetic in a five-quart jug plus a decent filter runs you roughly thirty-five to fifty dollars depending on the car. A shop doing the same work charges more, but not enormously more if you catch a coupon. If you're doing this purely to save money on a Civic, the math is thin. If you're doing it because you want to know the plug is tight and the right oil went in, the math is excellent.

Tools, one time

A 3/8-inch ratchet and a socket that fits the drain plug. Most are 14mm, 15mm or 17mm. Some are a hex key or a Torx bit, so check before you're lying under the car.

A torque wrench in the 10 to 80 lb-ft range. Sixty dollars, lasts forever, and it's the difference between confidence and hoping.

A drain pan that holds at least eight quarts and is low enough to slide under your car. Get one with a sealing lid and a pour spout. Open pans are how oil ends up on your shoes.

A filter wrench that actually fits. The cap-style ones that match your filter's diameter and flute count are far better than the universal band type, especially when the filter is buried. Take the old filter to the parts store if you're not sure.

Also: nitrile gloves, a couple of rags, a funnel, and a flattened cardboard box. The cardboard is for lying on and for catching drips, and it tells you things later.

Getting the car up, safely

Park on concrete that's level. Not a sloped driveway, not gravel, not grass. Pull the parking brake and chock the rear wheels.

Ramps are the easiest option for most people. Drive up slowly, in gear or in park, and have someone spot you the first time. If you use a floor jack instead, the car goes on jack stands at the manufacturer's lift points before any part of you goes under it. A hydraulic jack is a lifting tool, not a holding tool. Seals fail. People have died this way, and they died doing exactly what they'd done fifty times before.

Some cars sit high enough that you don't need to lift at all. If you can slide under on cardboard with the wheels on the ground, that's the safest version of this job.

Run the engine for two or three minutes first, then shut it off. Warm oil drains faster and carries more junk out with it. Fully hot oil will burn you, so don't do this straight off the highway.

Drain

Find the drain plug on the lowest point of the oil pan. On a lot of newer cars there's a plastic undertray with six to fourteen fasteners in the way. That's the part nobody mentions, and it's why your "twenty-minute job" took an hour the first time. Some trays have a hatch. Most don't.

Position the pan slightly offset from the plug, because oil comes out at an angle at first and goes straight down at the end. Break the plug loose with the ratchet, then spin it out by hand with a rag ready. It will drop into the pan. You will fish it out. Everyone does.

Open the hood and pull the oil fill cap while it drains. It vents the crankcase and it stops you from forgetting to put oil in, which is a genuinely common and genuinely catastrophic error.

Let it drain five to ten minutes, until it's dripping rather than running.

Wipe the plug, fit the new crush washer, thread it in by hand until it seats, then torque to spec. By hand first, always. Cross-threading a drain plug is a bad day.

The filter

Spin-on type: position the pan underneath, because the filter holds oil and it's coming out. Unscrew counterclockwise. Then run a finger around the mounting surface and make sure the old gasket came off with the filter. Wipe the surface clean.

Dip a finger in fresh oil and smear it around the new filter's rubber gasket. Thread it on by hand until the gasket touches, then tighten another three-quarter turn, or whatever the filter box says. No wrench. You need to remove this thing in six months.

Cartridge type: the filter lives in a plastic or metal housing on top of the engine, often with a special cap socket. The new filter comes with new O-rings, sometimes two or three of them, and you replace all of them. Lube them with fresh oil. Cap torque is low, often around 18 to 25 Nm, and plastic housings crack when you guess. Check the manual.

Fill, then check twice

Put a funnel in the fill hole and pour in about a half quart less than capacity. Cap on. Start the engine and watch the oil pressure light. It should go out within a few seconds. If it stays lit, shut it down immediately and find out why.

Let it idle thirty seconds while you look under the car for drips at the plug and the filter. Then shut it off and wait five minutes for the oil to settle back down.

Check the dipstick. Add in small amounts until you're at or just under the full mark. Overfilling isn't harmless. The crankshaft whips aerated oil into foam, and foam doesn't lubricate.

Reset the oil life monitor if your car has one. The procedure is in the manual, usually a sequence of button presses or a menu.

The used oil

Pour it into the empty jugs through the funnel. Punch the old filter and let it drain overnight into the pan, then bag it. Most auto parts stores take used oil free, typically up to five gallons a visit, and many take filters too. Call first. Pouring it down a drain or onto the ground is illegal nearly everywhere and it's a genuinely rotten thing to do.

When to just pay someone

If your car has a 14-bolt skid plate, a filter tucked behind the exhaust, or a factory service plan you've already paid for, hand it over. If you don't have level ground, hand it over. There's no virtue in doing it badly on a slope.

Leave the cardboard under the engine overnight. In the morning it tells you the truth: clean means you're done, one dark spot means go back and check the plug. That five seconds of reading a piece of cardboard has saved more engines than any tool in the box.