What happens when you change your oil
Replacing your car's oil means draining the old oil from the engine, replacing the oil filter, and filling the engine with fresh oil. You do this yourself by getting under the car, locating the drain plug (a bolt at the bottom of the engine), unscrewing it to let old oil flow into a pan, screwing the plug back in, swapping out the filter, and pouring new oil through the filler cap on top of the engine. The whole job takes 30 minutes to an hour if you have the right tools and know where everything is.
You need to do this because oil breaks down over time and loses its ability to protect your engine. Fresh oil keeps metal parts from grinding against each other, carries away heat, and prevents sludge buildup. Most cars need an oil change every 3,000 to 10,000 miles depending on the oil type and engine — check your owner's manual for your car's interval.
Key Takeaways
- You will need a socket wrench, an oil filter wrench, a drain pan, fresh oil (the correct type and amount for your car), and a new filter before you start.
- The oil drain plug is located underneath the engine and requires you to safely raise the car or work from below, so use jack stands or ramps — never rely on a jack alone.
- The oil filter screws onto the engine by hand and must be replaced at the same time as the oil; old filters contain dirty oil that contaminates fresh oil.
- Overfilling or underfilling the engine with oil damages the engine, so check the level with the dipstick after filling and add or remove oil to reach the correct mark.
- Dispose of old oil at a recycling center, auto parts store, or service station — pouring it down a drain or into the ground is illegal and harms the environment.
Gather your tools and materials before you start
You need the right oil for your car first. Open your owner's manual or look inside the fuel door — the manual will tell you the oil type (usually something like 5W-30 or 10W-40) and how much the engine holds (typically 4 to 6 quarts). Buy that exact type and amount, plus one extra quart in case you need to top off. Buy a new oil filter that matches your car's make, model, and year — the parts store can look this up for you if you give them your vehicle information.
For tools, you need a socket wrench that fits your drain plug (usually 13mm, 14mm, or 15mm — the parts store can tell you), an oil filter wrench (a metal band or cup that grips the filter), a drain pan to catch old oil (at least 6 quarts), and jack stands or ramps to safely raise the car. You will also need a rag or old towel, a funnel that fits your oil filler cap, and a dipstick (your car has one built in). If you do not have jack stands or ramps, buy them before you start — they cost $30 to $50 and are essential for safety.
Raise the car safely and locate the drain plug
Park on a level surface and let the engine cool for at least five minutes. If you have ramps, drive the front wheels onto them slowly and set the parking brake. If you are using a jack, place it under the frame (not the plastic bumper or body panel) at the jacking point marked in your owner's manual, raise the car a few inches, then slide jack stands under the frame on both sides. Lower the car onto the stands. Never work under a car supported only by a jack.
Crawl under the engine and look for the drain plug — it is a bolt sticking down from the bottom of the engine pan, usually on the passenger side. It will have a washer (a flat ring) under the bolt head. Place your drain pan directly underneath it. If you cannot see it clearly, use a flashlight. Once you have located it, you are ready to drain the oil.
Drain the old oil and replace the filter
Using your socket wrench, turn the drain plug counterclockwise to loosen it. Once it is loose enough, unscrew it by hand — it will be warm, so be careful. Let the oil drain completely into the pan; this takes 5 to 10 minutes. While you wait, locate the oil filter on the side of the engine (it looks like a metal cylinder about the size of a soda can). Wipe the area around it with a rag.
Once the oil has stopped dripping, wipe the drain plug clean with a rag and screw it back in by hand until it is snug. Do not overtighten it — hand-tight is enough. Now unscrew the old filter by turning it counterclockwise with your filter wrench. Oil will spill out, so keep the drain pan underneath. Once it is off, wipe the rubber gasket surface on the engine clean with a rag.
Take your new filter and coat the rubber gasket (the ring at the top) with a thin layer of fresh oil from your new oil container. Screw the new filter onto the engine by hand until the gasket touches the engine, then turn it another three-quarter turn. Do not use the wrench — hand-tight is correct. Overtightening damages the filter and makes it hard to remove next time.
Fill the engine with fresh oil
Lower the car back to the ground if you used a jack and stands. Open the hood and locate the oil filler cap on top of the engine — it usually has an oil can symbol on it. Unscrew it and set it aside. Place your funnel in the opening and slowly pour in the new oil. Pour in about three-quarters of the amount your manual says the engine holds, then stop.
Replace the oil filler cap and start the engine. Let it run for 30 seconds to circulate the new oil through the filter, then turn it off. Wait two minutes for the oil to settle back into the pan, then check the level.
Check the oil level and finish
Open the hood again and locate the dipstick — it is a long thin rod with a handle, usually yellow or orange. Pull it straight out. Wipe it clean with a rag, then reinsert it all the way until it clicks or seats. Pull it out again and look at the oil level. The dipstick has two marks: a minimum line and a maximum line. The oil should be at or just below the maximum line.
If the level is below the maximum line, add a little more oil through the filler cap opening and check again. If it is above the maximum line, you overfilled it — use a turkey baster or syringe to remove a small amount of oil from the filler opening. Once the level is correct, replace the dipstick and the filler cap.
Dispose of old oil properly
Old oil cannot go in the trash or down a drain. Take the drain pan to an auto parts store (most accept old oil for free), a quick-lube shop, a recycling center, or a municipal hazardous waste facility. Many stores that sell oil will take it back. Call ahead to confirm they accept it, then pour it into a container with a lid and transport it safely in your car.
If you replaced the filter, ask the store whether they will take it as well. Some will; others require you to dispose of it separately. The store can tell you where to take it if they do not accept it.
Frequently Asked Questions
How do I know what oil type my car needs?
Check your owner's manual — it will list the oil type (like 5W-30 or 10W-40) and the capacity in quarts. You can also find this information on a sticker inside the fuel door or by asking an auto parts store with your vehicle's year, make, and model.
What if I cannot get under the car safely?
If you do not have ramps or jack stands, or if you are not comfortable working under a car, take it to a quick-lube shop or service station. An oil change typically costs $30 to $75 depending on the oil type and your location. This is safer than working without proper equipment.
Can I reuse the old oil filter?
No. The filter contains dirty oil and particles that will contaminate fresh oil. You must replace it every time you change the oil. A new filter costs $8 to $15.
What happens if I overfill the engine with oil?
Overfilling can damage the engine by causing oil to foam, reducing its ability to protect moving parts. It can also cause oil to leak from seals. Always check the dipstick and keep the level between the minimum and maximum marks.
How often should I check my oil between changes?
Check the level once a month or before long trips. Pull out the dipstick, wipe it, reinsert it fully, then pull it out again and read the level. If it is below the minimum mark, add a quart of the correct oil type and recheck.