What happens during an oil change and why you need one

An oil change means draining the old oil from your engine, replacing the oil filter, and filling the engine with fresh oil. Oil lubricates moving parts, reduces heat, and carries away dirt and debris. Over time it breaks down and loses its ability to protect the engine. Running on old oil causes wear, overheating, and eventual engine damage.

Most cars need an oil change every 3,000 to 10,000 miles, depending on the engine type and oil grade. Check your owner's manual for the exact interval for your vehicle. Some newer cars with synthetic oil can go longer between changes. Skipping oil changes is one of the fastest ways to shorten an engine's life.

Key Takeaways

  • You will need an oil drain pan, a wrench to fit your drain plug, a new oil filter, fresh oil in the correct grade and amount, and jack stands if you need to lift the car.
  • The process takes 30 minutes to an hour and involves draining old oil, removing and replacing the filter, and adding new oil to the correct level.
  • Check your owner's manual for the oil type, capacity, and drain plug location specific to your vehicle.
  • After adding new oil, run the engine for a minute, turn it off, wait five minutes, then check the level on the dipstick to confirm it is correct.

Tools and materials you will need

Gather these items before you start: an oil drain pan (at least 6 quarts), a wrench or socket that fits your drain plug, an oil filter wrench, a new oil filter, fresh motor oil in the correct grade and amount, and old rags or paper towels. If your car sits low to the ground, you will also need a jack and jack stands to safely raise it.

Your owner's manual tells you the oil grade (such as 5W-30 or 10W-40) and the total capacity in quarts. Buy oil that matches both. The oil filter part number is usually printed in the manual or on the old filter itself. Do not guess on either — using the wrong oil or filter can damage the engine or cause the filter to fail.

How to drain the old oil

Warm the engine by running it for two or three minutes, then turn it off. Warm oil flows faster and drains more completely. Wait a minute for it to cool slightly so you do not burn yourself. If you need to raise the car, use the jack to lift it safely and secure it with jack stands under the frame — never work under a car supported only by a jack.

Locate the drain plug underneath the engine. Slide the drain pan under it. Use the wrench to turn the plug counterclockwise and unscrew it by hand once it is loose. Let the old oil drain completely into the pan — this takes five to ten minutes. Wipe the drain plug clean with a rag and inspect the rubber washer. If it is cracked or flattened, replace it with a new one before reinstalling the plug.

Once the oil stops dripping, screw the drain plug back in by hand, then tighten it with the wrench. Do not overtighten — you only need it snug enough that it does not leak. Overtightening strips the threads and makes the next change harder.

Removing and replacing the oil filter

The oil filter is usually a cylindrical canister mounted on the side of the engine. Position the drain pan underneath it to catch the oil that spills when you remove it. Use the oil filter wrench to turn the filter counterclockwise until it comes free. Finish unscrewing it by hand and set it aside.

Wipe the filter mounting surface on the engine clean with a rag. Take the new filter and apply a thin layer of fresh oil to the rubber gasket on top — this helps create a good seal and makes removal easier next time. Screw the new filter on by hand until the gasket contacts the engine, then turn it another three-quarters of a turn. Hand-tight is correct; do not use the wrench to tighten the new filter.

Adding new oil and checking the level

Locate the oil filler cap on top of the engine — it usually has an oil can symbol. Unscrew it and set it aside. Pour in the amount of oil listed in your manual, usually between 4 and 6 quarts. Pour slowly and stop partway through to check the level, since overfilling is common and damages the engine.

Replace the oil filler cap. Start the engine and let it run for about one minute. This circulates the new oil and fills the filter. Turn the engine off and wait five minutes for the oil to settle. Pull out the dipstick, wipe it clean on a rag, reinsert it fully, then pull it out again to read the level. The oil should reach the full mark or fall between the minimum and maximum marks. Add a little more if it is low, or drain a small amount if it is over.

Check underneath the car for leaks around the drain plug and filter. If you see drips, turn off the engine and tighten the plug or filter slightly. Once you confirm there are no leaks, you are done. Record the mileage and date in your maintenance log so you know when the next change is due.

Common mistakes to avoid

Overfilling the oil is the most common error. Too much oil foams, loses its lubricating ability, and can damage seals and gaskets. Use the dipstick to verify the level after adding oil, not the amount listed on the bottle. Bottles vary in size and your engine capacity is what matters.

Forgetting to replace the oil filter washer or installing the new filter too tight also causes leaks. The washer is a small rubber ring on the old filter — if it sticks to the engine, remove it before installing the new filter. Hand-tighten the new filter only; the wrench is for removal, not installation.

Running the engine before checking the level is another trap. Always verify the oil level after the engine has run and cooled slightly. The dipstick reading is the only reliable way to know if you have added the right amount.

What to do with the old oil

Never pour old oil down the drain or into the ground. It contaminates water supplies and soil. Most auto parts stores accept used oil for free, even if you did not buy oil from them. Some gas stations and quick-lube shops also take it. Call ahead to confirm hours and whether they accept oil in containers you bring, or if they provide their own.

If you drained the oil into a pan, let any sediment settle to the bottom, then pour the clean oil into a sealed container for transport. Label it clearly as used motor oil. Keep the container upright during transport to prevent spills.

Frequently Asked Questions

Can I change the oil without raising the car?

Yes, if your car sits high enough off the ground to slide under and reach the drain plug. Many sedans and crossovers have enough clearance. If you cannot fit under safely, use a jack and jack stands. Never work under a car supported only by a jack — it can slip and cause serious injury.

What if I spill oil on the driveway?

Spilled oil stains concrete and harms the environment. Contain it immediately with sand, kitty litter, or oil absorbent material. Let it sit for 15 minutes, then sweep it up and dispose of it as hazardous waste. Many communities have hazardous waste collection days. Do not hose it down — that spreads it and makes cleanup harder.

How do I know if I bought the right oil filter?

Check the part number on the old filter and compare it to the new one before you start. Your owner's manual also lists the correct filter. If the new filter does not fit the mounting surface or the threads do not match, you have the wrong one — return it and get the correct part.

What happens if I forget to add new oil after draining?

Do not start the engine. Running an engine without oil causes immediate damage to bearings and moving parts. If you realize the mistake before starting, add oil right away. If you already started it, stop immediately and do not run it again until you have added oil and let it circulate.

Can I mix different oil brands or grades?

Mixing brands is safe — they all meet the same standards. Mixing grades is riskier. If you must add oil between changes, use the same grade listed in your manual. If you accidentally mixed grades, do not worry; just perform your next oil change on schedule and use the correct grade going forward.