What happens when you change your engine oil
Changing engine oil means draining the old oil from your engine, replacing the oil filter, and filling the engine with fresh oil. The oil circulates through your engine to lubricate moving parts, cool the engine, and carry away dirt and metal particles. Over time, oil breaks down from heat and collects contaminants, so it stops protecting your engine as well. Replacing it keeps your engine running smoothly and extends its life.
You can do this yourself with basic tools if you have access to your car's underside, or you can take your car to a shop and have someone else do it. Either way, the process takes 30 minutes to an hour. Most cars need an oil change every 3,000 to 10,000 miles, depending on your car's age, the type of oil you use, and what your owner's manual says.
Key Takeaways
- Check your owner's manual to find out what type and amount of oil your specific car needs, because using the wrong oil can damage your engine.
- You will need an oil drain pan, a wrench to remove the drain plug, an oil filter wrench, and new oil and a new filter — all available at auto parts stores.
- The oil drains from a plug underneath your engine; you remove the old filter by hand or with a wrench, then screw on the new one by hand until it is snug.
- After filling with new oil, start the engine and let it run for a minute, then turn it off and wait five minutes before checking the oil level on the dipstick.
Find the right oil type and amount for your car
Open your owner's manual and look for the section on maintenance or fluids. It will tell you the oil viscosity (the thickness rating, like 5W-30 or 10W-40) and the total capacity in quarts. Write these down before you go to the store, because using the wrong viscosity can reduce fuel economy or leave your engine unprotected in cold weather.
If you do not have your manual, you can find this information on the manufacturer's website by entering your vehicle's year, make, and model, or you can call your car's dealership with that information and they will tell you over the phone. Do not guess or use what worked for someone else's car — the wrong oil matters.
Gather tools and materials before you start
You will need an oil drain pan (a shallow rectangular container to catch old oil), a wrench that fits your drain plug (usually 13mm, 14mm, or 15mm), an oil filter wrench (a metal band or socket that grips the filter), the correct new oil and new oil filter for your car, and jack stands or ramps if you need to raise the car to reach the drain plug underneath.
Most auto parts stores sell oil change kits that include the oil, filter, and a drain pan for less than buying them separately. Ask the staff to confirm the filter fits your car before you leave. Keep old newspapers or cardboard under your workspace — spilled oil stains concrete and soil.
Drain the old oil from underneath your engine
Warm up your engine by running it for two or three minutes, then turn it off and wait five minutes. Warm oil flows faster than cold oil. Raise your car on jack stands or drive it onto ramps so you can reach the underside safely — never work under a car supported only by a jack.
Locate the drain plug, a bolt on the lowest part of the oil pan underneath the engine. Place your drain pan directly underneath it. Use your wrench to loosen the plug by turning it counterclockwise, then unscrew it by hand the rest of the way. Oil will pour out — let it drain completely, which takes five to ten minutes. Once the flow slows to drips, wipe the plug clean with a rag and set it aside.
Remove the old filter and install the new one
The oil filter is a cylindrical canister bolted to the side of the engine. Use your oil filter wrench to loosen it by turning counterclockwise, then unscrew it by hand. Oil will spill out, so keep your drain pan underneath. Wipe the rubber gasket (the flat ring) off the engine block with a clean rag.
Take your new filter and coat the rubber gasket on top with a thin layer of new oil — this helps it seal properly. Screw the new filter onto the engine by hand until the gasket touches the engine block, then turn it another three-quarters of a turn. Do not use the wrench to tighten it; hand-tight is correct. If you over-tighten it, the gasket will tear and the filter will leak.
Refill with new oil and check the level
Lower your car back to the ground. 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. Pour in the amount of new oil your manual specified, then replace the cap and screw it down hand-tight.
Start the engine and let it run for one minute. The new oil will circulate through the engine and the filter will fill with oil. Turn off the engine and wait five minutes for the oil to settle back into the pan. Pull out the dipstick (a long metal rod with markings on it), wipe it clean on a rag, reinsert it all the way, then pull it out again and read the level. The oil should reach the "full" mark. If it is low, add a little more oil and check again. Do not overfill — too much oil can damage seals and gaskets.
Dispose of old oil properly
Old engine oil is toxic and cannot go in the trash or down the drain. Most auto parts stores that sell oil will take used oil for free, even if you did not buy it from them. Pour your old oil into a clean container with a lid, load it in your car, and bring it to the store. Some recycling centers also accept used oil.
If you changed the filter, the old filter also contains oil and should be recycled. Many stores will take filters for free as well. Call ahead to confirm what your local store accepts.
Frequently Asked Questions
How do I know when my oil needs changing?
Check your owner's manual for the recommended interval — it is usually every 3,000 to 10,000 miles depending on your car's age and oil type. Many modern cars have an electronic oil-life monitor that displays a message on the dashboard when oil change is due. You can also check the oil level with the dipstick every month; if it is dark brown or black instead of amber, the oil is breaking down and should be changed soon.
What if I spill oil on my driveway?
Spread cat litter, sand, or oil absorbent over the spill to soak it up, then sweep it into a bag and dispose of it with your used oil. For large spills, contact your local environmental agency — they may have cleanup resources. Do not hose it down; oil runs into storm drains and contaminates groundwater.
Can I change my oil if I do not have a garage or driveway?
If you rent or live in an apartment, changing your own oil is difficult and may violate your lease. A quick-lube shop or dealership can change your oil in 30 to 45 minutes for a reasonable cost. Call ahead to ask about pricing and whether you need an appointment.
Do I need to change the oil filter every time I change the oil?
Yes. The filter traps contaminants and becomes saturated over time. If you do not replace it, the old filter will restrict oil flow and defeat the purpose of the fresh oil. A new filter costs $8 to $15 and is worth the protection.
What should I do with the drain plug after I remove it?
Wipe it clean and keep it. You will screw it back in after the old oil drains. If the plug has a crush washer (a soft metal ring underneath the bolt head), replace it with a new one each time — a used washer will not seal properly and the plug may leak.