What changing your oil actually does
Oil is the fluid that keeps your engine's moving parts from grinding against each other and wearing out. As your engine runs, the oil gets dirty — it picks up metal particles, dust, and burnt fuel — and it breaks down from heat. Old, dirty oil stops protecting your engine as well as fresh oil does. Changing your oil means draining out the old oil and replacing it with new oil, and usually swapping out the oil filter (a small canister that traps particles) at the same time.
Your car's owner manual tells you how often to change the oil — typically every 3,000 to 10,000 miles, depending on your car's age and the type of oil you use. Skipping oil changes leads to engine damage that costs thousands to repair, so this is one of the few maintenance tasks that actually saves you money in the long run.
Key Takeaways
- Oil changes take 30 minutes to an hour and cost between $25 and $75 at a shop, or less if you do it yourself and already own the tools.
- You need to know your car's oil type and capacity before you buy oil — check your owner manual or look it up by year, make, and model online.
- The oil filter must be changed at the same time as the oil, and it screws on by hand without special tools.
- Most cars need an oil change every 5,000 to 7,500 miles with conventional oil, though newer cars with synthetic oil may go 10,000 miles or longer.
Getting the supplies you need
Before you start, you need to know what oil your car takes. Open your owner manual and look for "oil capacity" and "oil type" — you will see something like "5 quarts of 5W-30" or "4 quarts of 0W-20". The numbers and letters describe the oil's thickness at different temperatures; your car needs the exact type listed, not a guess. If you do not have the manual, search online for your car's year, make, and model plus "oil type" and you will find the answer in seconds.
Buy a jug of new oil in the correct type and quantity — most auto parts stores sell it for $5 to $15 per quart. You also need a new oil filter that matches your car; the parts store employee can look it up if you give them your car's year, make, and model. An oil filter costs $5 to $15. If you are doing the work yourself, you will also need an oil drain pan (a shallow tray to catch the old oil), a wrench or socket set to remove the drain plug, and an oil filter wrench (a tool that grips the filter to unscrew it). Many people borrow these tools or buy a basic set for $20 to $40.
Draining the old oil
Park your car on a level surface and let the engine cool for at least five minutes — warm oil drains faster, but hot oil can burn you. Locate the oil drain plug underneath the engine; it is a bolt sticking down from the engine pan. Slide your drain pan underneath it, then use your wrench to unscrew the plug by turning it counterclockwise. The old oil will pour out — this takes a few minutes. Once the flow slows to a drip, wipe the drain plug clean with a rag and screw it back in by hand, then tighten it with your wrench. Do not over-tighten; snug is enough.
Next, locate the oil filter — it is a cylindrical canister about the size of a soda can, usually mounted on the side of the engine. Position your drain pan underneath it, then use your oil filter wrench to turn the filter counterclockwise until it comes free. Unscrew it the rest of the way by hand. A little old oil will spill, so move slowly. Before you install the new filter, dip your finger in new oil and rub it around the rubber gasket (the ring) on top of the new filter — this helps it seal properly. Screw the new filter on by hand until the gasket touches the engine, then turn it another three-quarters of a turn. Again, snug is the goal, not maximum tightness.
Adding new oil and checking the level
Pop open your hood and locate the oil filler cap — it is usually on top of the engine and has an oil can symbol on it. Unscrew the cap and set it aside. Pour in the amount of new oil your manual specified, a little at a time. After you have added most of it, wait a minute for the oil to settle in the pan, then check the level with your dipstick.
Pull out the dipstick (a long thin rod, usually with a yellow or orange handle), wipe it clean on a rag, push it all the way back in, then pull it out again and look at where the oil reaches. The dipstick has two marks — "low" and "full" — and the oil should be between them, ideally at the full mark. If it is low, add a little more oil and check again. Once the level is right, screw the oil filler cap back on and close your hood.
Starting the engine and checking for leaks
Start your engine and let it run for about a minute. The oil light on your dashboard (usually a red oil can symbol) should turn off within a few seconds — if it stays on, turn off the engine and check that the drain plug and filter are tight. Once the light is off, turn off the engine and wait five minutes for the oil to settle, then check the dipstick level one more time. It should still be at or near the full mark.
Look underneath the car for any drips around the drain plug or filter. A drop or two is normal, but a steady drip means something is not tight enough. If you see a leak, tighten the drain plug or filter a bit more and check again after a few minutes of running. Once everything looks dry, you are done. Write down the date and mileage in your owner manual so you know when the next change is due.
When to take your car to a shop instead
If your car is very low to the ground, you may not be able to fit under it safely without a jack and jack stands — equipment that costs money and requires care to use correctly. If you do not have access to these tools or feel uncomfortable working under a car, a shop is the safer choice. Some newer cars also have cartridge-style filters that sit on top of the engine and require a special socket to remove; if your car has one, a shop can do the job faster than you can learn the process.
Most independent repair shops charge $30 to $50 in labor plus the cost of oil and filter, so a full change runs $50 to $75. Chain shops like Jiffy Lube or Valvoline charge similar amounts. Dealerships usually cost more — $75 to $150 — but they use the exact oil your car's manufacturer recommends and they keep records in your service file. If your car is still under warranty, check whether the warranty requires you to use the dealership for service; most do not, but some do.
Frequently Asked Questions
Can I mix different oil types together?
Mixing conventional and synthetic oil is safe in an emergency, but it defeats the purpose of synthetic oil's longer lifespan. Mixing two different weights — like 5W-30 and 10W-30 — is also safe but not ideal. Always use the exact type your manual specifies for your next change.
What should I do with the old oil?
Never pour old oil down a drain or into the ground — it is toxic and illegal in most places. Take it to an auto parts store, a quick-lube shop, or a recycling center; most accept old oil for free or a small fee. Many stores that sell oil will take it back if you bought oil from them.
How do I know if my oil is dirty before the scheduled change?
Check the dipstick every month or two. If the oil looks black and thick, it is dirty, but if it is still brown and flows easily, it is fine. You can also look at the oil on the dipstick under good light — if you cannot see the dipstick through the oil, it is time for a change.
What if the oil light stays on after I change the oil?
The light usually means low oil level or a loose drain plug or filter. Check the dipstick first — if the level is low, add more oil. If the level is correct, tighten the drain plug and filter, run the engine for a minute, and check again. If the light still stays on, the sensor itself may be faulty and needs a mechanic's diagnosis.
Is synthetic oil worth the extra cost?
Synthetic oil costs two to three times more per quart than conventional oil, but it lasts longer — often 10,000 miles or more instead of 5,000 to 7,500. If you keep your car for many years, synthetic saves money over time because you change it less often. Check your manual to see what your car's manufacturer recommends.