What happens when you change your engine oil
Changing your engine oil means draining the old oil from your engine, replacing the oil filter, and filling the engine with fresh oil. The old oil has collected dirt, metal particles, and moisture over time and loses its ability to protect engine parts. Fresh oil lubricates moving parts, reduces friction, and helps your engine run cooler and last longer.
You can do this yourself with basic tools in about 30 to 45 minutes, or you can have a shop do it. The cost of materials for a DIY oil change is typically $20 to $50, depending on the type and amount of oil your engine needs. A shop oil change usually costs $30 to $75 for conventional oil, more for synthetic blends or full synthetic.
Key Takeaways
- You need your owner's manual to find the correct oil type, viscosity grade, and capacity for your specific engine.
- Drain the old oil while the engine is warm but not hot, replace the filter, and refill with the exact amount and grade your manual specifies.
- Check your oil level with the dipstick or electronic gauge after the engine has sat for a few minutes so the oil settles.
- Most engines need an oil change every 3,000 to 10,000 miles, depending on oil type and your vehicle's age — your manual states the interval for your car.
Finding the right oil for your engine
Your owner's manual lists the oil viscosity grade and type your engine requires. Viscosity is the oil's thickness, shown as a number like 5W-30 or 10W-40. The "W" stands for winter; the first number indicates how the oil flows in cold weather, and the second number shows how it flows at operating temperature. Using the wrong viscosity can reduce fuel economy, increase wear, or cause the engine to run too thick or too thin.
Oil comes in three main types: conventional mineral oil, synthetic blend, and full synthetic. Conventional oil is cheapest and works well for older engines and normal driving. Synthetic blend splits the difference in cost and performance. Full synthetic lasts longer between changes and handles extreme temperatures better, but costs more upfront. Your manual may recommend one type or allow you to choose based on your driving conditions and budget.
Check how much oil your engine holds — this is also in your manual, usually listed in quarts or liters. Most engines hold between 4 and 6 quarts. Buy one extra quart in case you need to top off after the initial fill.
Tools and materials you will need
A basic oil change requires an oil drain pan (to catch old oil), a wrench or socket set to remove the drain plug, an oil filter wrench or strap wrench to remove the old filter, a funnel, fresh oil, and a new oil filter. You may also need jack stands and a jack if your car sits too low to slide under safely — never rely on a jack alone.
Wear old clothes and gloves; oil stains are permanent. Have rags or paper towels on hand to wipe spills and check the dipstick. If you do not own these tools, you can rent or borrow most of them, or buy a basic set for $30 to $50 that will last for many oil changes.
Steps to drain and replace the oil
Start with the engine warm but not hot — run it for a minute or two, then turn it off and wait five minutes. Warm oil flows faster and drains more completely, but hot oil can burn your skin. Locate the oil drain plug underneath the engine (your manual shows where) and position the drain pan beneath it. Loosen the plug with a wrench, then unscrew it by hand and let the old oil drain completely — this takes 5 to 10 minutes.
While the oil drains, locate the oil filter, usually a cylindrical canister on the side of the engine. Position the drain pan underneath it, then use an oil filter wrench to loosen it about three-quarters of a turn. Finish unscrewing by hand, being careful not to spill old oil on the engine. Wipe the filter mounting surface clean with a rag.
Take the new filter and explore 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 touches the mounting surface, then turn it another three-quarters of a turn. Do not over-tighten; hand-tight is correct.
Wipe the drain plug clean, replace the washer if it came with the new plug, and screw it back in by hand. Tighten it with a wrench, but do not over-tighten — a snug fit is all you need. Place the drain pan aside and position the funnel in the oil filler cap opening on top of the engine. Pour in the amount of oil your manual specifies, usually in half-quart increments to avoid overfilling.
Checking the oil level and running the engine
After you have poured in the recommended amount, replace the oil filler cap and start the engine. Let it run for 30 seconds to a minute so the new oil circulates through the filter and engine. Turn off the engine and wait at least five minutes — this allows the oil to drain back into the pan and gives you an accurate reading.
Pull out the dipstick (a long metal rod with markings on it), wipe it clean with a rag, reinsert it fully, then pull it out again and check the level. The oil should be between the minimum and maximum marks. If it is below the minimum, add a quarter-quart at a time and recheck. If it is above the maximum, you have overfilled — you will need to drain a small amount out through the drain plug.
Some newer cars have an electronic oil level gauge instead of a dipstick. Check your manual for how to read it. Once the level is correct, you are done. Dispose of the old oil at a recycling center, auto parts store, or service station — most accept it for free or a small fee. Never pour it down a drain or into the ground.
When to change your oil and what to track
Oil change intervals vary widely. Older cars and those using conventional oil typically need a change every 3,000 to 5,000 miles. Cars using synthetic blend oil may go 5,000 to 7,500 miles. Full synthetic oil can last 7,500 to 10,000 miles or more. Your owner's manual states the interval for your specific vehicle and engine — follow that rather than a general rule.
Some cars have an oil change reminder light that comes on based on mileage or engine hours. If your car has one, note when it appears and plan your change around that schedule. Keep a straightforward log of the date, mileage, oil type, and filter used each time you change the oil. This record helps you spot patterns and proves you have maintained the vehicle if you ever sell it.
Common mistakes to avoid
Overfilling the oil is the most common error. Too much oil can damage the engine by creating excess pressure, foaming the oil, and causing leaks. Always check the level after the engine has sat for several minutes and add oil in small amounts. Underfilling is also harmful — low oil starves the engine of lubrication and causes rapid wear. Check the level every month between changes.
Forgetting to replace the oil filter wastes the benefit of fresh oil; the filter clogs and restricts flow. Never reuse an old filter. Tightening the drain plug or filter too much can strip the threads and cause leaks that are expensive to repair. Hand-tight plus a quarter turn with a wrench is the correct approach.
Mixing oil types is generally safe — you can top off with a different brand or viscosity in an emergency — but it reduces the performance of both oils. Stick to the type and grade your manual specifies whenever possible.
Frequently Asked Questions
Can I change my oil if the engine is cold?
Cold oil drains slowly and incompletely, leaving more old oil in the engine. Warm the engine by running it for a minute or two, then wait five minutes before draining. This gives you a complete drain without the risk of burns from hot oil.
What should I do with the old oil?
Take it to a recycling center, auto parts store, or service station — most accept used oil for free or charge a small fee. Never pour it down a drain, into the ground, or into the trash. One quart of oil can contaminate 250,000 gallons of water.
Is synthetic oil worth the extra cost?
Synthetic oil lasts longer between changes and protects better in extreme heat or cold, so it can save money over time if you keep the car for many years. Conventional oil is fine for normal driving and regular maintenance. Your manual may recommend one type or allow you to choose based on your climate and driving habits.
What if I accidentally overfilled the oil?
Drain a small amount through the drain plug until the level is correct. Overfilled oil can damage seals and cause leaks, so do not ignore it. Check the level again after the engine has sat for several minutes.
How do I know if my oil filter is on tight enough?
Screw the filter on by hand until the rubber gasket touches the mounting surface, then turn it another three-quarters of a turn. You should not need a wrench to tighten it further. Over-tightening makes it difficult to remove next time and can damage the filter or mounting surface.