A conventional oil change replaces your engine oil with new mineral oil and swaps out the filter
A conventional oil change is the most straightforward type of oil service. A technician drains the old mineral oil from your engine's oil pan, replaces the oil filter, and refills the engine with new conventional (mineral) oil. The whole process typically takes 30 to 45 minutes at a shop, though it can be done at home if you have basic tools and a safe place to work underneath your vehicle.
Conventional oil is refined directly from crude oil and contains no synthetic additives. It costs less than synthetic or synthetic-blend oils, which is why many owners choose it for older vehicles or when budget is the primary concern. However, conventional oil breaks down faster under heat and stress, so it requires more frequent changes — typically every 3,000 to 5,000 miles, depending on your vehicle and driving conditions.
Key Takeaways
- Conventional oil changes involve draining mineral oil, replacing the filter, and adding new mineral oil — a process that takes 30 to 45 minutes.
- Conventional oil costs less upfront than synthetic alternatives but needs to be changed more often, usually every 3,000 to 5,000 miles.
- The oil filter must be replaced at every conventional oil change to prevent dirt and debris from circulating through the engine.
- Conventional oil is suitable for older vehicles, high-mileage engines, and situations where cost is the main factor, but it offers less protection in extreme temperatures.
How the process works step by step
The technician begins by warming the engine slightly so the oil flows more easily. The vehicle is then raised on a lift or jack, and the drain plug — a bolt at the bottom of the oil pan — is removed. Old oil drains into a collection pan and is disposed of according to environmental regulations.
Once the pan is empty, the drain plug is reinstalled and tightened. The technician then locates the oil filter (usually a cylindrical canister on the side of the engine) and unscrews it by hand or with a filter wrench. A new filter is installed, and the technician adds the correct amount and type of new conventional oil through the filler cap on top of the engine. Finally, the oil level is checked with the dipstick to confirm it is at the proper mark.
Why conventional oil breaks down faster
Conventional mineral oil is a refined product of crude oil with minimal processing. It contains natural impurities and lacks the chemical additives found in synthetic oils that help it resist heat, oxidation, and sludge buildup. As your engine runs, the oil is exposed to temperatures that can exceed 200 degrees Fahrenheit, which causes the oil molecules to break apart and lose their protective properties.
This breakdown happens gradually. Over time, the oil becomes thinner, loses its ability to coat engine parts, and allows more friction and wear. Sludge — a thick, dark deposit — can also form as the oil oxidizes. This is why conventional oil needs to be changed more frequently than synthetic alternatives. Neglecting to change conventional oil on schedule can lead to increased engine wear, reduced fuel economy, and potentially costly damage.
Conventional versus synthetic oil: the main differences
Conventional oil is cheaper per quart and per change, making it attractive for budget-conscious owners. Synthetic oil is engineered in a laboratory to have a uniform molecular structure, which allows it to withstand higher temperatures, resist breakdown longer, and provide better protection in extreme cold. Synthetic oil typically lasts 7,500 to 10,000 miles or longer before needing a change.
Synthetic-blend oil is a middle ground — it mixes conventional and synthetic oils to offer better protection than conventional alone at a lower cost than full synthetic. Many newer vehicles come filled with synthetic or synthetic-blend oil from the factory. If your owner's manual specifies conventional oil, switching to synthetic will not harm your engine, but it is not necessary and adds cost. If your manual specifies synthetic, using conventional oil may void your warranty and reduce engine protection.
When conventional oil is the right choice
Conventional oil is most practical for older vehicles, especially those with over 100,000 miles. Engines that have been running on conventional oil for years are designed around its properties, and switching to synthetic offers minimal benefit. Conventional oil is also a sensible choice if you drive short distances, keep your vehicle for only a few years, or prioritize lowest upfront cost over longer intervals between changes.
Vehicles used for light, predictable driving — such as commuting on highways at steady speeds — also do well on conventional oil. High-performance vehicles, those towing heavy loads, or cars driven in extreme heat or cold benefit more from synthetic oil's superior protection, even though the cost per change is higher. Check your owner's manual to see what your manufacturer recommends; that is the safest guide for your specific engine.
What happens to the old oil
Used conventional oil cannot be poured down a drain or thrown in the trash. It is classified as hazardous waste and must be recycled or disposed of properly. Most shops that perform oil changes collect used oil in sealed containers and send it to a recycling facility. Used oil is often re-refined into new oil or processed into other products like hydraulic fluid or fuel.
If you change your own oil, you can take the used oil to a recycling center, an auto parts store that accepts it, or a municipal hazardous waste collection event. Many locations accept used oil for free. Never dispose of it yourself in ways that could contaminate soil or water.
Tools and supplies needed for a DIY conventional oil change
If you choose to change your own oil, you will need the correct type and amount of conventional oil (check your owner's manual), a new oil filter that matches your vehicle, an oil drain pan, a wrench or socket set to remove the drain plug, and an oil filter wrench to unscrew the old filter. A jack and jack stands are essential if you need to raise the vehicle to reach the drain plug safely. Some vehicles have easier access and do not require lifting.
Wear old clothes or an apron, as spilled oil stains. Work on a level surface and allow the engine to cool slightly before starting — hot oil can burn skin. After draining, dispose of the old oil properly. The entire job typically takes 45 minutes to an hour for someone doing it for the first time. If you are unsure about any step, a shop visit is safer and not much more expensive.
Frequently Asked Questions
How do I know what type of conventional oil my car needs?
Your owner's manual lists the correct oil viscosity — usually something like 5W-30 or 10W-40. The first number is the oil's flow in cold weather, and the second is its flow at operating temperature. Buy the exact grade listed; using the wrong viscosity can affect fuel economy and engine protection.
Can I mix conventional oil with synthetic oil?
Yes, mixing them is safe and will not damage your engine. However, the protective benefits of synthetic oil are diluted by the conventional oil, so you lose some of the advantages. If you are switching from conventional to synthetic, you can do so at your next oil change without flushing the old oil first.
What does the oil filter do?
The oil filter traps dirt, metal particles, and sludge that circulate through the engine. Over time, it becomes clogged and can no longer filter effectively, which is why it must be replaced at every oil change. A clogged filter forces oil to bypass the filter media, allowing contaminants to circulate and damage engine parts.
Is it cheaper to change my own oil?
DIY oil changes cost less per change — usually $20 to $40 for oil and filter versus $50 to $75 at a shop — but only if you already have the tools. If you need to buy a jack, stands, and wrenches, the initial investment may not pay off unless you plan to change your oil many times. Shops also dispose of used oil properly, which is included in their price.
What happens if I go too long between conventional oil changes?
The oil becomes thinner and loses its ability to protect engine parts. Sludge builds up, friction increases, and wear accelerates. Over time, this can lead to reduced fuel economy, rough idling, engine noise, and eventually serious damage like bearing wear or valve problems. Sticking to the recommended interval is the cheapest way to keep your engine healthy.