Regular and synthetic oils are used to lubricate engine parts. This oil protects the moving parts of the engine, thus preventing wear and tear. Most people do not understand the differences between regular and synthetic oils, which lead to too many misconceptions.
Most vehicle models today can use both regular and synthetic oil. One confusing question about the oil is can you use regular oil after synthetic?
We will be answering this question in a while. We shall also learn more about regular and synthetic oil, their advantages and disadvantages.
What Is Synthetic Oil?
Synthetic oil is made from chemical compounds that contain some petroleum elements combined with highly refined crude oil, organic, and inorganic compounds.
In addition to synthetic oils, there are also synthetic blends that combine synthetic oils with traditional petroleum-based oils.
Synthetic motor oils were developed to address a major problem all combustion engines deal with each time they are started: oil and solvents do not mix well together.
Engine oil is designed to lubricate moving parts inside the engine, especially around the combustion chamber. However, most fuels are petroleum based and are solvents, which literally wash away conventional oil which coats components.
Synthetic oil typically lasts longer than conventional motor oil, which can reduce overall costs or at least help justify the higher price tag that comes with synthetic oils.
For example, a person might change his or her oil every 3,000 miles with regular oil and only every 5,000 miles with synthetic oil.
Pros of Synthetic Oil
#1. Outstanding Wear Protection.
Engine components constantly contact each other when the vehicle is moving at high speeds, thus leading to friction. This friction between the parts makes them prone to break down and wear and tear.
Motor oils act as a protective barrier between the engine components. Synthetic oils retain wear and tear protection properties for a longer time compared to regular oils. This keeps the vital engine parts in good condition, thus increasing their useful life.
#2. Stable Viscosity.
Synthetic oils have a higher viscosity index making it stable in a wide range of temperatures. It means that the oil’s viscosity does not change much during engine start-up and different operating conditions.
#3. Keeps the Engine Cleaner.
The oil picks up deposits as it circulates through the engine. After some time, regular oils form sludge, which minimizes the engine’s efficiency, thus reducing its useful life.
Synthetic oils resist the formation of deposits and sludge in engines because they are made with fewer impurities. If your engine already has sludge, the best synthetic oils will clean it after an oil change.
#4. Optimized Fuel Consumption.
Synthetic oils have a longer lifespan compared to regular oil. Synthetic oils should be recommendable changed at around 5000 to 7000 miles while some brands can eve 15000 to 25000 miles.
#5. Better Turbocharger Protection.
Most vehicles these days are made with turbochargers and smaller engines. Synthetic oils flow faster to the crucial parts, thus creating proper lubrication to the engine requirements. Full synthetic oils help to keep your turbocharged car to its maximum performance.
Cons of Synthetic Oil
#1. Expensive.
Synthetic oil is pricier compared to regular oil.
#2. Not ideal for new vehicles.
New cars require the friction created when they use regular petroleum-based oils to work efficiently.
What Is Regular Oil?
Regular oil is also known as mineral oil or conventional oil. This oil works as a lubricant for automotive. These oils have been in like since 1908. It is made from petroleum, which is a natural substance.
Today, regular oils are mixed using base oils made of polyinternal olefins (PIO), hydrocarbons, and polyalphaolefins (PAO), thus organic compounds comprising hydrogen and carbon purely.
One of the greatest advantages of regular oil is its inexpensive nature. Conventional oils need to be changed regularly since they have a short lifespan. If you remember to change the oil as required regularly, it will prevent the engine components from wear and tear.
Regular oils tend to break down much easily compared to synthetic oil. This makes the oil contaminated by forming sludge and deposits, which negatively affects the engine components.
Sludge prevents the engine parts from moving properly, reducing engine performance, and shortening its useful life. Less sludge on the engine components also gives one better fuel economy.
The viscosity of conventional oils is not as stable as that of synthetic oil. These oils are very reactive to temperatures and thus are not ideal for operations with extremely low temperatures or very high temperatures.
Regular oil should be changed every three months or 3000 miles or the one that comes first.
When choosing regular oil, check its viscosity grade. Check the vehicle manual on what the manufacturer recommends.
The viscosity numbers show how well the oil will flow both at low temperatures and operating temperatures. Check the motor oil regularly, which will help you know when the oil needs to be changed or when it is running low.
Pros of Regular Oil
#1. Inexpensive.
Conventional or regular oil is the cheapest oil you will get for your automobiles. This oil can even be three times cheaper than synthetic oils.
#2. Ideal for New Cars.
Most manufacturers use regular oil during the assembly of the vehicle. Car owners are advised to continue using conventional oil when the vehicle is new.
A new vehicle needs a break-in period of around 5000 miles. This oil from the manufacturer should be changed after six months or 6000 miles or the one that comes first.
#3. Ideal for Old Vehicles.
Regular oil is the ideal oil for old vehicles like those manufactured before 2000. Engines that have gone beyond their prime cannot utilize the benefits of synthetic oils, leaving conventional oils as the only choice.
#4. Readily Available.
Unlike synthetic oils, regular oils are quite easy to get in your nearby local shops. This means that whenever you need it, you will get it without too much hassle.
Cons of Regular Oil
#1. Low Stability.
When conventional oils are exposed to high temperatures, they become thinner. This, therefore, does not prevent engine parts from friction, thus leading to wear and tear.
#2. More Break Down.
Regular oil tends to break down more, thus leading to a shorter lifespan. Therefore, you must keep on changing to keep the engine parts well protected than using conventional oils.
#3. More Impurities.
Just like we have said above, regular oil breaks down fast, and this makes them prone to the building of sludge and deposits.
When conventional oil breaks down, it sticks to different engine components forming sludge or deposits. These deposits eventually lead to damage to engine parts.
#4. Cannot be used in Extreme Temperatures.
Regular oil is not ideal for operations in high temperatures. This oil breaks down when exposed to extremely high temperatures, and lubrication is minimal when used in low temperatures.
Types of Motor Oil
To fully grasp the implications of mixing synthetic oil with regular oil, it’s essential to familiarize ourselves with the various types of motor oil available. While the question of mixing oil may imply a binary choice, there are four basic varieties of motor oil:
- Conventional or Regular Motor Oil: Derived from crude oil, conventional motor oil is commonly used in vehicles with simple engine designs.
- Synthetic Motor Oil: Synthetic motor oil is chemically engineered, resulting in uniform molecules that contain fewer impurities compared to conventional oil.
- Synthetic Blend Motor Oil: As the name suggests, synthetic blend motor oil is a mixture of synthetic and conventional oils. It offers improved resistance to oxidation and rust, making it a popular choice for extreme weather conditions.
- High-Mileage Motor Oil: Formulated specifically for vehicles with over 75,000 miles, high-mileage oil helps reduce oil burn-off and leaks.
Each type of oil has its unique properties and is scientifically formulated to cater to specific engine requirements. Mixing these oils will not enhance engine performance or oil quality.
Basic Differences Between Regular And Synthetic Oils
Most folks grab a bottle of oil based on price or whatever’s on sale, but not every oil is built the same. At the core, synthetic oil comes from highly refined base oils and added chemical boosters.
Regular oil—also called conventional oil—starts with crude oil and gets minimal processing. That one change makes a pretty big difference in how both oils perform inside your engine.
The big win with synthetic oil is how it handles heat and stress. It’s built in a lab to stay slick, so it doesn’t thicken or break down as quickly.
Regular oil, on the other hand, loses its punch faster especially if you drive hard, deal with stop-and-go traffic, or face hot summers.
Synthetics also fight “sludge,” the gunk that can choke oil passages in your engine. That means less risk of weird noises, ticking, or even expensive breakdowns.
Here’s a simple look at how they stack up:
| Feature | Regular Oil | Synthetic Oil |
|---|---|---|
| Base Material | Crude oil refined a few times | Engineered base + additives |
| Resistance to Heat | Breaks down at 250-275°F | Stable up to 400°F and above |
| Protection Against Sludge | Mediocre | Very high |
| Longevity | 3,000-5,000 miles | 7,500-15,000 miles |
| Price (per quart) | $4–$6 | $8–$12 |
One quick fact here: over 70% of new cars in 2025 recommend or require synthetic oil, according to recent automaker specs.
That means automakers are betting on its benefits for engine life and efficiency. Sure, regular oil is cheaper, but those savings disappear if you have to change it more often or face costly repairs down the line.
It’s not just hype—synthetic oil is lab-tested to last longer, protect better, and deal with the heat and grime that today’s engines throw at it. Understanding these differences helps you pick the right oil and avoid surprises under the hood.
Can You Use Regular Oil after Synthetic Oil?
Both synthetic and regular oil has the same application, and thus you can use regular oil after synthetic oil. People have had the misconception that when you start using synthetic oil, you cannot go back to regular oil, which is just but a myth.
These two oil types are different, but not that much. Both regular and synthetic oils are made with lubricants to keep a vehicle’s engine performance steady and smooth.
You may ask yourself, what happens if you use regular oil instead of synthetic? Changing from synthetic oil to regular oil will not have any effect on the vehicle’s well-being. The only notable effect you will note is the change in engine performance.
Synthetic is much better compared to regular oil in terms of quality. Therefore, you will note a change in the steady performance of the engine.
The fact that the engine’s performance decreases is what makes people think that changing from synthetic to regular is impossible.
Experts recommend that you stick to synthetic oil instead of downgrading. This is because synthetic oil will keep your vehicle’s engine healthy and increase its useful life.
If you decide to change from synthetic oil to regular oil, there are several considerations you need to consider.
It is recommendable to gradually change since you are introducing a completely new oil type to the engine. First, the switch from synthetic oil to semi-synthetic oil.
Switching from synthetic to semi-synthetic gets the engine to prepare for conventional oil. You can now introduce the regular oil completely later in the second phase. It is also recommendable to change the oil filter as you change the oil type.
It is vital to consider your car model when contemplating changing car oil from synthetic to regular. Newer vehicles have the upper hand when it comes to switching oil types.
Old model vehicles may get some leakage problems when switching from one oil type to the other. It is, therefore, important to consult your vehicle manufacturer before you carry out the oil change.
What Happens If You Use Regular Oil Instead Of Synthetic?
Now, we will debunk the reasons as to what would happen if you were to switch to regular oil instead of synthetic oil for your car. Some vehicle owners might think that is it bad to switch from synthetic to regular oil. We will help clear the confusion.
#1. The raw manufacturing.
As compared to synthetic oil, regular oil gets distilled and refined from crude oil. Crude oil is a naturally occurring liquid fossil fuel.
On the other hand, companies prepare synthetic oil artificially from chemical compounds with the goal of mimicking the properties of natural oil.
They manufacture it as per the demands of modern-day vehicles. You can search online if you want the answer to what happens if you use regular oil instead of synthetic oil in your car.
#2. No engine cleanliness and protection.
As regular oil moves through the vehicle’s engine, it degrades slowly thus leaving harmful deposits and even leading to the formation of sludge. It can affect the performance of your car’s engine and the life of the vehicle.
The synthetic oil comes with minimal impurities and is more sludge-resistant. It keeps the car engine cleaner and makes its operation smooth and long.
#3. Regular oil = Bad choice for driving in extreme temperatures.
Your car engine generates heat while you are on a long ride with your friends. It causes the oil to break down. Synthetic oil works better in extreme conditions as it is manufactured using precise engineering. It can easily resist heat allowing your car engine to last longer.
The regular oil would take longer to heat up to its ideal viscosity in cold temperatures. It might not offer the lubrication required when you are trying to start your vehicle.
#4. The cost increases.
Your car mechanic might charge you approximately $30 to $45 for a conventional oil change. The full synthetic oil costs around $70 to $100 depending on the vehicle. The full synthetic might cost you a bit more, but it increases the engine life by two to three times.
A regular oil change would cost you anywhere from $120 to $180. It is a bit more expensive than synthetic oil. You can also check online to get the best car engine oil-changing tips.
#5. Lesser oil longevity.
Do you want to know what happens if you use regular oil instead of synthetic? The synthetic oil requires changing after a minimal driving of 10,000 to 15,000 miles. The regular oil needs to change every 3000 to 5000 miles.
How to mix synthetic oil with regular oil?
The following content is just to show you how mixing oils are done as we recommend using synthetic oils only for proper engine mileage. Mix regular oils with synthetic only as of the last result if synthetic oils are not available in your area.
- Be sure that your car is parked on safe and level ground before you start.
- Power off the engine.
- Check engine oil.
- Add regular oil to synthetic oil. If you’re low on synthetic oil and there are no synthetic oil products nearby, you may use regular oil.
- Replace the engine oil cap.
When it comes to replacing regular oil with conventional oil, it’s recommended that you drain all regular oil and replace it with synthetic oils.
Doing so will help remove all impurities present in conventional oil before adding safe, pure, and dependable synthetic engine oil.
But when you’re switching from synthetic to conventional oil, there’s no need to drain synthetic oils from the engine as you are replacing clean oil with more impurities.
All you need to do is to check the level engine oil levels first and simply add the regular oil to the engine oil cap.
Mixing oils won’t damage your car but will greatly affect the efficiency of your vehicle and the cleanliness of your car’s engine.
As always, if you’re unsure as to how your car engine oil is replaced, ask a professional car repair expert to help you out.
FAQs.
Q: What Happens If You Use Regular Oil Instead Synthetic?
Using regular oil instead of synthetic oil may have some effects on the performance of your engine. Synthetic oils are of higher quality than regular oil, and it, therefore, improve the performance of your vehicle engine.
Regular oil is of low quality, and it does not offer good lubrication in extreme temperatures. It breaks down fast in higher temperatures, thus putting the engine parts at risk of wear and tear.
It also breaks down to form sludge and deposits, which reduces engine performance. In cold temperatures, regular oil takes time to heat up and get to the ideal viscosity.
Therefore, if your car is recommended for synthetic oil, it is recommendable to stick to it to get the engine’s best performance.
Q: Can You Use Synthetic Oil After Using Regular Oil?
Yes. It is possible to use synthetic oil after using regular oil. However, it is important to contact your car manufacturer on whether you can use synthetic oil on the engine. Moving from regular oil to synthetic oil is an upgrade.
You will experience a noticeable change in the performance of the engine. Synthetic oil makes the engine performance smoother and steady. You will also not need to keep on changing since it lasts longer.
Q: Should I Use Synthetic Oil In My High Mileage Car?
You can use synthetic oil on high mileage vehicles, but again, it depends on the car manufacturer’s recommendations.
A vehicle has high mileage when it goes beyond 75,000 miles. If the high mileage vehicle has been well maintained, synthetic oils will help to protect the engine and extend its useful life.
You can consider using some synthetic oils designed especially for high-mileage vehicles. When switching to synthetic oil in higher mileage vehicles, consult the manufacturer to get advice on the exact oil to use on the vehicle.
Q: Is It a Good Idea To Put Synthetic Oil In Older Cars?
If you can use synthetic oil on older cars will depend on the car manufacturer. Some car manufacturers of older models recommend using regular oil, and changing it to synthetic oil may cause some Engine Problems, such as oil leakage.
However, if the manufacturer allows you to use synthetic oils, it will be ideal. Synthetic oil will enhance vehicle engine protection, thus increasing their useful life.
Therefore, the right thing is to consult the vehicle manufacturer and clarify if you can use synthetic oil on your old car model.
Q: Will Synthetic Oil Make Your Engine Last Longer?
Yes, synthetic oil is high-quality oil, and it makes your engine last longer. This oil has a stable viscosity and is thus ideal for high-temperature operations. Synthetic oils offer better lubrication, thus preventing wear and tear.
This improves the engine mileage making it last for a longer period. To get the best from synthetic oil, it is advisable to change it at least 6,000 miles. However, some synthetic oils can go up to 15,000 miles.
Final Words
By now, I am confident that I have answered the question; can you use regular oil after synthetic? Synthetic oil is more beneficial compared to regular oil since it has low viscosity, great lubrication, and a longer lifespan, among other pros.
The oil is ideal for luxury car engines, towing and high loads, high-performance engines, and driving.
However, if you still want to switch from synthetic to regular, it is still possible. The difference you will note after the switch is decreased engine performance.
Whichever oil you decide to use, remember to change it on time. This helps the vehicle to run efficiently and smoothly. It protects the engine from breaking down and reduces the number of times you go to the mechanic for maintenance and repair.