The Benefits of Synthetic Oil vs Conventional Motor Oil

Synthetic motor oil has been around and popular for decades, yet some vehicle owners still prefer conventional oil.

While conventional oil isn’t necessarily a bad choice, it doesn’t offer the same level of performance or protection as synthetic, and YES on an annual basis, conventional oil may be costing you more!

To help you make an informed decision, this guide explores the differences, benefits, and best use cases for both oil types, with insights straight from Ethan, the owner of Ethan’s Honest Automotive.

What Is Conventional Motor Oil?

Conventional motor oil is derived directly from crude oil, a naturally occurring substance extracted from the ground. After refining, this oil is blended with chemical additives to improve performance.

However, since conventional oil contains molecules of varying sizes, it doesn’t always perform consistently across extreme temperatures. That’s where synthetic oil stands out.

What Is Synthetic Motor Oil?

Synthetic oil is engineered in a lab by chemically modifying base oils. The result is a lubricant with uniform molecules and enhanced performance characteristics. While it became popular in the 1980s, it’s now the go-to oil for most modern vehicles.

Types of Synthetic Oil

• Full Synthetic Oil

Made entirely from synthetic base oils like polyalphaolefins (PAO) or esters, offering superior protection and performance in high-stress environments.

• Synthetic Blend Oil

A mix of synthetic and conventional oils, designed to offer some of the benefits of synthetic at a lower cost.

• High-Mileage Synthetic

Formulated with additives to reduce wear, seal leaks, and support engines with over 75,000 miles.

• High-Performance Synthetic

Ideal for racing or performance vehicles needing the highest level of heat resistance and lubrication.

• Fuel-Efficient Formulas

Engineered with friction-reducing additives to improve MPG and reduce engine strain.

• Various Viscosity Grades

Synthetic oils are available in multiple grades, such as 0W-20, 5W-30, and 10W-40, each designed for different operating temperatures and engine types.

Your owner’s manual should indicate which types of synthetic motor oil are right for your vehicle. However, if you have any questions, you can discuss the issue with a trusted mechanic, such as those at Ethan’s Honest Automotive. Our experts are well-versed in all types of motor oil and can help you pick the option that is best for your engine and driving style.

What Are Some of the Key Differences Between Synthetic and Conventional Oil?

Which Oil Offers Better Engine Protection?

High temperatures: Synthetic oil resists breakdown and maintains its viscosity better, providing stable lubrication during heavy loads or hot climates.

Low temperatures: It flows more easily when cold, reducing wear during cold starts and providing faster engine protection.

Uniform lubrication: Its consistent molecular size leads to smoother, more stable lubrication across engine parts.

Which Oil Performs Better in Modern Engines?

Modern engines — especially turbocharged ones — generate more heat and require oil that flows quickly. Synthetic oil excels in these conditions and is often needed by newer vehicles.

Ethan: “Newer cars, especially turbocharged ones, need synthetic. They’re built differently — smaller engines, more heat. Synthetic helps with performance and emissions.”

Is Conventional Oil Still a Good Choice?

It can be, especially for older, well-maintained vehicles not designed for synthetic. However, it may need to be changed more frequently to prevent buildup and wear.

If you’re going to do conventional, take Ethan’ advice…

Ethan: “I’m a bit old-fashioned. I go by the 3,000-mile rule. It keeps seals soft and prevents oil breakdown.”

However Ethan does this even with synthetics!

Expert Q&A with Ethan – Owner of Ethan’s Honest Automotive

Do You Follow the Old-Fashioned Oil Change Rule for Your Own Cars?

Ethan: “For my wife’s 2014 GMC Acadia, I use full synthetic and change it every 6,000 miles. It’s got nearly 200,000 miles and runs like a dream. Same with my diesel truck — I use a secondary filter and it’s clean as a pin inside.”

Do You Often See Old Vehicles That Are Clean Inside?

Ethan: “About 80% of the older cars we see are in good shape — if they’ve been maintained. The ones that haven’t? They’re usually already dead.”

What’s Your Take on Synthetic vs. Conventional Oil?

Ethan: “Whether it’s conventional or synthetic, oil’s job is the same — lubricate, create pressure, and keep the engine clean.

For conventional, I’m a bit old-fashioned. I go by the 3 months or 3,000 miles rule. It keeps seals soft and prevents oil breakdown that can lead to sticky buildup and clogged passageways.”

“Because it comes from nature, conventional oil has molecules of varying sizes. This variation means it doesn’t always perform well across different temperatures. Additives help, but it’s still less reliable than synthetic.”

“I had a client that drove 3,000 miles every two weeks, so let his car go more than 3,000.

So, if the Recommended Miles Are Reached Every Two Weeks, Would You Recommend Changing Oil Every Two Weeks?

Ethan: “No, not at all. That guy I mentioned just drove a ton of miles. He hit 3,000 miles in two weeks! I stick to 3,000 miles, but that’s just my personal preference.”

What About Newer Cars That Use Synthetic Oil?

Ethan: “Newer cars, especially turbocharged ones, need synthetic. They’re built differently — smaller engines, more efficient, more heat. Thin synthetic oil helps with performance and emissions, but it also means more oil consumption.

Some manufacturers like Volkswagen suggest 10,000-mile intervals, and they design for that. But again, I prefer to change earlier than that to avoid buildup and engine problems.”

Are Newer Cars Just Allowed to Burn Oil?

Ethan: “Yes. Some, like Subarus or Chryslers, allow for about a quart every 1,000 to 1,500 miles. That’s normal for them. But if you’re not checking your oil, you can run dry before your next scheduled oil change. I’ve seen multiple Subarus blow up because owners didn’t check between 5,000–8,000 miles.”

Is Checking Oil Just as Important as Changing It?

Ethan: “I teach my wife and kids to check it at every gas fill-up or at least every 1,000 miles. You can’t just rely on oil change intervals.”

Do You Recommend Changing Oil More Often Than the Manual Says?

Ethan: “Definitely. For me, it’s cheap insurance. Most people forget or delay maintenance. I’d rather spend a bit more changing oil than replacing an engine.”

Does Synthetic Oil Save Money Over Time?

Ethan: “It might, depending on the manufacturer. Some, like Toyota, allow for longer intervals. But in most cases, synthetic recommendations aren’t that much longer. I like the peace of mind.”

Do Any 2025 Vehicles Still Require Conventional Oil?

Ethan: “Not that I know of. Most now require synthetic. And honestly, I don’t even see 2025 cars in my shop yet — they’re still under warranty.”

Will Conventional Oil Eventually Become Obsolete?

Ethan: “Exactly. Eventually, there’ll only be synthetic. That’s where it’s headed.”

Do You Still Carry Synthetic Blend Oil?

Ethan: “Yes, I carry full synthetic and synthetic blend. The blend works fine in older cars and simplifies things. The lowest grade I stock is a synthetic blend.”

So, Just Two Oils Now?

Ethan: “Right. I stock multiple weights, because that still matters. But those are the two types I use.”

Benefits of Synthetic Oil Compared to Conventional Oil

Improved Viscosity and Temperature Resistance

Synthetic oil flows better at extreme temperatures due to its consistent molecular structure.

Enhanced Engine Protection

It reduces wear, prevents sludge, and keeps internal parts cleaner over time.

Better Fuel Efficiency

Synthetic oil’s low viscosity means less friction and better MPG, especially in modern engines.

Longer Oil Change Intervals

Synthetic oil lasts longer before breaking down, resulting in fewer oil changes over time.

Compatibility With Advanced Engines

As engines evolve, they need oil that meets tighter tolerances and higher performance demands, which synthetic oil provides.

When Conventional Oil Still Makes Sense

Use Conventional Oil If:

• Your vehicle was designed with it in mind
• You drive short distances and don’t put much stress on the engine
• You’re doing frequent oil changes anyway
• You’re trying to save money on up-front maintenance costs (even though you aren’t for vehicles that require half has many oil changes if you use full synthetic, therefore you are losing money on up-front maintenance costs, AND potentially accelerating future repairs)

Ethan: “It (conventional) still works — especially in older vehicles that are well-maintained. But synthetic covers more bases.”

There are several types of synthetic motor oils, each formulated with specific base oils. We list the different types of synthetic oil below. Each will be formulated to meet the diverse needs of different engines and driving conditions.

Keep in mind that this is not a comprehensive list of synthetic oil types. Instead, these are the most popular varieties of synthetic oil currently on the market.

In Summary: Benefits of Synthetic Oil vs. Conventional Oil

Overall, the choice between synthetic oil and conventional oil is an important decision for vehicle owners. However if you have a newer car, your choice is: what the manufacturer recommends or a third-party equivalent. In other words you don’t really have a choice. But there are some things you can ask yourself (see below) to fine tune the oil change intervals.

What you are looking for is optimal engine performance, longevity, and overall driving experience. Synthetic oil, with its advanced formulation and superior properties, offers a range of benefits that make it a compelling option for any car built in the 90s or later.

Synthetic oil, especially full synthetic oil, does have a higher transaction cost. But don’t let this fool you. The total yearly cost can be anywhere from double to slightly more and in some cases, even less than conventional oil maintenance costs on an annual basis; even when you follow the manufacturers guidelines!

Do the following and we think you’ll come to the right conclusion on the right balance between oil change intervals and cost:

• Write down how many courts of oil your vehicle requires between full and the bottom of the dipstick

• Find out if your car burns through oil, and how fast it burns through oil

• Find out what your manufacturer recommends for oil change intervals

• Find out what online forum experts recommend for your make and model, and see if you can stretch it?

Now do the math, and we bet for 90% of readers that you will find that full synthetic for your daily driving vehicle will make economic sense!

Still unsure? Come by Ethan’s Honest Automotive. Whether you’re driving an older truck or a turbocharged crossover, our team will help you choose the right oil based on your car’s age, engine, mileage, and driving habits.