What happens when you replace an oil filter

Replacing your oil filter means unscrewing the old cylindrical filter from the engine, draining the old oil inside it, and screwing on a new one. The filter traps dirt and metal particles that circulate through your engine oil—over time it gets clogged and stops working well. A new filter keeps your oil clean and your engine protected. Most people do this every time they change the oil, which is usually every 3,000 to 10,000 miles depending on your car and the type of oil you use.

The job takes 10 to 20 minutes once you know where the filter is. You do not need special training, but you do need the right tools and a safe way to get under the car. If you are not comfortable working under a vehicle or do not have a safe lift, a mechanic or quick-lube shop can do this for you for $20 to $75 in labor.

Key Takeaways

  • You will need a filter wrench, an oil drain pan, a new filter that matches your car's make and model, and a way to safely raise the car or access the filter from above.
  • The filter screws on by hand—you hand-tighten it until it contacts the engine, then turn it another three-quarter turn, never with a wrench.
  • Old oil inside the filter will spill, so drain it into a pan and dispose of it at a service station, auto parts store, or recycling center, not in the trash or down a drain.
  • If the filter is stuck, soak it with penetrating oil for a few minutes, then use a filter wrench with steady pressure rather than jerking force.
  • A new filter costs $8 to $25 depending on your vehicle; buying the correct part number beforehand saves time and frustration.

Locate your filter and gather tools

Open your owner's manual or search your car's make, model, and year online to find where the oil filter sits on your engine. On most cars it is on the side or bottom of the engine, a cylindrical canister about 4 inches tall. Some newer cars have a cartridge-style filter under a plastic cap on top of the engine instead. Your manual will show you which type you have and where to find it.

Before you start, buy a new filter with the correct part number for your car. The part number is printed on your old filter or in your manual. Bring your car's year, make, and model to an auto parts store and they will hand you the right one. You will also need a filter wrench (a metal band or cup that grips the filter), an oil drain pan, a socket wrench set or screwdriver to remove any covers, and old rags or paper towels. Wear old clothes—oil stains.

Safely access the filter

If the filter is on the bottom of the engine, you will need to raise the car safely. Use a jack and jack stands, never rely on a jack alone—a falling car causes serious injury. Place the jack stands on the frame, not on plastic trim or fuel lines. If you are not confident using a jack, ask a friend to help or take the car to a shop.

If the filter is accessible from above without raising the car, position your drain pan underneath it before you loosen anything. Oil will drip out, and the pan catches it so you can dispose of it properly. If the filter is hard to reach, you may need to remove an engine cover or air intake hose first—your manual shows which bolts to unbolt.

Remove the old filter

Position your drain pan under the filter. Grip the filter with your filter wrench and turn it counterclockwise to loosen it. Once it is loose enough to turn by hand, unscrew it the rest of the way by hand. Tip it so the opening faces down into the drain pan and let the old oil drip out for a minute or two. Wipe the filter mounting surface on the engine with a clean rag to remove any dirt or old rubber seal.

If the filter will not budge, do not force it—you can crack the filter housing. Spray the filter with penetrating oil (like WD-40), wait five minutes, then try again with steady, even pressure on the wrench. If it still will not move, stop and take the car to a mechanic rather than risk damaging the engine.

Install the new filter

Before you screw on the new filter, check that the rubber seal on the bottom is clean and dry. Dip your finger in fresh oil and rub a thin coat around the rubber seal—this helps it seat properly and makes the next change easier. Do not use old oil from the drain pan.

Screw the new filter on by hand until the rubber seal touches the engine. Then turn it another three-quarter turn (about 270 degrees) by hand. Do not use a wrench to tighten it—hand-tight is correct. If you over-tighten it with a wrench, you will crack the seal and it will leak.

Dispose of old oil and check your work

Pour the old oil from your drain pan into a sealed container. Take it to a service station, quick-lube shop, or auto parts store that accepts used oil—most do this for free. Never pour oil down a drain, into the trash, or onto the ground. It contaminates water and soil and is illegal in most places.

Lower the car back to the ground if you raised it. Start the engine and let it run for 30 seconds, then turn it off. Wait a minute and check the oil level on the dipstick or digital gauge. Top it off if needed. Look under the car or under the hood where the filter sits—you should see no drips. If oil is leaking from the filter, turn off the engine, let it cool, and tighten the filter another quarter turn by hand.

When to call a professional

If the filter is stuck and will not loosen after soaking with penetrating oil, stop and take the car to a mechanic. Forcing a stuck filter can crack the housing and cause expensive damage. If you do not have a safe way to raise the car or access the filter, a shop can do the whole job quickly and cheaply.

If you see oil leaking after you finish, and tightening the filter does not stop it, the seal may be damaged or the housing may be cracked. Have a mechanic inspect it before you drive the car far. A small leak now is easier and cheaper to fix than engine damage from running low on oil.

Frequently Asked Questions

Can I change the oil filter without changing the oil?

Yes. The filter and oil serve different purposes—the filter traps particles, and the oil lubricates and cools. You can replace the filter alone, though most people do both at the same time since you are already under the car. If you change only the filter, you still need to dispose of the old oil that drains out of it.

How tight should the new filter be?

Hand-tight plus three-quarter turn. Once the rubber seal touches the engine, turn it by hand until you feel resistance, then turn it another 270 degrees. Do not use a wrench—over-tightening cracks the seal and causes leaks. If you cannot remember how much you turned it, loosen it and start over.

What if I cannot find the oil filter on my car?

Check your owner's manual first—it has a diagram showing the exact location. If you do not have the manual, search online for "[your year, make, model] oil filter location" and you will find photos and videos. If the filter is truly hard to access, a mechanic can show you where it is and do the replacement for a small fee.

Can I reuse an oil filter?

No. Once a filter is removed, it cannot be sealed back on safely. The rubber seal loses its shape and will not hold pressure. Always use a new filter, and dispose of the old one in the trash or at a recycling center that accepts them.

How do I know what filter to buy?

Look at your current filter—the part number is printed on the side. Write it down and take it to an auto parts store, or search the part number online. You can also give the store your car's year, make, and model and they will look up the correct filter for you. Buying the right part beforehand saves a trip back to the store.