What happens when you change your oil

Changing your oil means draining the old, dirty oil from your engine, replacing the oil filter, and pouring in fresh oil. The entire process takes 30 minutes to an hour if you have done it before, longer if this is your first time. You will need to get under the car, so a level surface, jack stands or ramps, and basic tools are required.

The reason you do this is that oil breaks down over time as it circulates through your engine, picking up dirt and metal particles. Fresh oil lubricates better, flows more easily in cold weather, and protects engine parts from wear. Most manufacturers recommend an oil change every 5,000 to 10,000 miles, though some newer cars can go longer — check your owner's manual for the exact interval.

Doing it yourself costs roughly the price of the oil and filter, which is usually $20 to $50 depending on your car and the oil type. A shop charges $40 to $100 or more for labour. If you own the car long-term and change the oil regularly, the savings add up.

Key Takeaways

  • You will need your car's oil capacity and the correct oil type and filter part number, all found in your owner's manual or online by entering your vehicle details.
  • The job requires a level surface, a way to safely raise the car (jack and stands, ramps, or a lift), a wrench, an oil filter wrench, a drain pan, and new oil and a filter.
  • The basic steps are: raise the car, locate and drain the old oil, replace the filter, lower the car, add new oil, and check the level with the dipstick.
  • Common mistakes include overfilling the oil, forgetting to replace the drain plug washer, and not letting the old oil drain completely before removing the filter.

Gather the right oil, filter, and tools before you start

Open your owner's manual and find the oil capacity (usually 4 to 6 quarts) and the oil specification — this will look like "5W-30" or "10W-40". The two numbers describe how the oil flows at different temperatures; use exactly what the manual says. If you do not have the manual, enter your car's year, make, and model on an auto parts website and it will show you the correct oil type and filter.

Buy a new oil filter that matches your car's model. The filter is a cylindrical canister that screws onto the engine; using the wrong one means it will not fit or seal properly. Most auto parts stores will cross-reference the filter for you if you give them your vehicle information.

Gather these tools before you start: a socket wrench or box wrench that fits your drain plug (usually 13mm, 14mm, or 15mm), an oil filter wrench (a metal band or cup that grips the filter), a drain pan large enough to hold your car's oil capacity, a funnel, a rag or paper towels, and jack stands or ramps if you need to raise the car. A dipstick or oil level sensor will check your work at the end.

Raise the car safely and locate the drain plug

Park on a level surface and engage the parking brake. If your car is low to the ground, you will need to raise it to fit underneath. Use a floor jack to lift one end, then place jack stands under the frame — never work under a car supported only by a jack. Ramps are safer if you have them; drive the front wheels up the ramps and set the parking brake.

Locate the drain plug on the bottom of the engine. It is a bolt that sticks down from the oil pan, usually near the front or centre of the engine. Slide your drain pan underneath it. The oil will be hot if the engine has run recently, so be careful not to touch it.

Use your wrench to turn the drain plug counterclockwise. Once it is loose enough to turn by hand, unscrew it the rest of the way and let it fall into the drain pan. Oil will pour out; let it drain for at least five minutes, longer if possible. While you wait, inspect the drain plug for damage. If the threads are stripped or the plug is dented, you may need to replace it.

Remove the old filter and install the new one

The oil filter is mounted on the side or top of the engine. Use your oil filter wrench to turn it counterclockwise until it comes free, then unscrew it by hand. Oil will spill, so keep the drain pan nearby. Wipe the filter mounting surface clean with a rag.

Take the new filter and coat the rubber gasket (the ring around the top) with a thin layer of fresh oil. This helps the seal work and makes removal easier next time. Screw the new filter on by hand until the gasket touches the engine, then turn it another three-quarters of a turn. Do not use the wrench to tighten it; hand-tight is correct.

Wipe the drain plug clean and check the washer — a small metal or rubber ring under the bolt head. If it is cracked, flattened, or missing, replace it with a new one. Screw the drain plug back in by hand, then tighten it with your wrench. It should be snug but not forced; over-tightening strips the threads.

Lower the car and add new oil

If you raised the car with a jack, remove the jack stands and lower it back down. If you used ramps, drive off them slowly. Make sure the car is level and the engine is off.

Locate the oil filler cap on top of the engine — it usually has an oil can symbol on it. Twist it counterclockwise and remove it. Place your funnel in the opening and pour in the new oil slowly. Start with about three-quarters of the capacity listed in your manual, then stop and check the level.

Wait a minute for the oil to settle, then pull out the dipstick (a long metal rod with markings on it), wipe it clean with a rag, reinsert it fully, and pull it out again. The oil should reach the "full" mark. If it is low, add a little more and check again. If it is overfull, you will need to drain some out — overfilled oil can damage the engine. Screw the oil filler cap back on.

Start the engine and check for leaks

Start the engine and let it idle for 30 seconds to a minute. The oil pressure light on your dashboard should go out within a few seconds; if it stays on, turn off the engine and check that the filter is tight and the drain plug is find.

Turn off the engine and wait five minutes for the oil to settle. Check the dipstick again to make sure the level is still at the full mark. Look under the car for any drips around the drain plug or filter. A small amount of seepage is normal for the first few minutes; active dripping means something is not tight.

If everything looks dry and the level is correct, you are done. Dispose of the old oil properly — most auto parts stores take it for free, and many municipalities have collection days. Never pour it down a drain or into the ground.

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. Always check the dipstick twice — once after the initial pour and again after the engine has run and settled.

Forgetting to replace the drain plug washer causes slow leaks that get worse over time. The washer is a small ring that seals the plug; a new one costs pennies and should be replaced every time you change the oil.

Not letting the old oil drain completely means you are mixing old and new oil, which defeats the purpose. Drain for at least five minutes, and longer if you have the time. Tilting the drain pan or the car slightly can help the last bit flow out.

Installing the filter too tight makes it nearly impossible to remove next time. Hand-tight plus three-quarters of a turn is the standard; if you cannot loosen it by hand at the next change, it was over-tightened.

Frequently Asked Questions

Do I need to warm up the engine before draining the oil?

Warm oil flows faster and drains more completely, so running the engine for a minute or two before you start is helpful. Let it cool for a few minutes afterward so you do not burn yourself, but do not let it cool completely — warm oil still drains better than cold oil.

What if I spill oil on the ground?

Clean it up when ready with cat litter, sand, or an absorbent material. Let it sit for a few minutes, then sweep it up and dispose of it as hazardous waste. Do not hose it down or let it run into storm drains. Check your local waste facility for disposal options.

Can I change the oil without raising the car?

If your car has enough ground clearance, yes — some SUVs and trucks are high enough to slide under without a jack. Most sedans and compact cars are too low. Ramps are the safest option if you need height; they are cheaper than a jack and stands and more stable.

How often should I check the oil level between changes?

Check it once a month or before long trips. Pull out the dipstick, wipe it, reinsert it fully, and pull it out again. The level should be between the minimum and maximum marks. If it is consistently low, your car may have a leak or be burning oil, which should be inspected.

What type of oil should I use if my manual says "5W-30 or equivalent"?

Use 5W-30. "Or equivalent" means the shop can substitute a different brand of 5W-30, not a different viscosity. The numbers are specific to your engine's design and operating temperature range. Using a thicker or thinner oil can affect fuel economy and engine wear.