Difference Between Synthetic and Fully Synthetic Oil

What’s the key difference between synthetic and fully synthetic oil? If you’ve been searching for the right engine oil, you’ve probably seen the terms synthetic oil and fully synthetic oil. At a glance, they may seem like the same thing—but there’s a big difference that can affect how your engine performs and how often you need oil changes.

Having used different oils over the years, I can confidently say that nothing beats AMSOIL in terms of protection, performance, and long-term value. Let’s look at what sets synthetic and fully synthetic oils apart—and why I always choose AMSOIL for my own vehicles.

What Is Synthetic Oil?

Synthetic oil is a blend—it combines conventional mineral oil with synthetic base oils. This mixture improves performance over regular oil, but it doesn’t deliver the full benefits of a true synthetic.

Most synthetic blends offer better resistance to breakdown and sludge compared to conventional oil, but they still contain impurities and lack the high-temperature stability that full synthetic oils provide.

What Is Fully Synthetic Oil?

Fully synthetic oil is made using chemically engineered base oils designed for performance and purity. These oils are free from the impurities found in crude oil and are built from the ground up to handle extreme temperatures, reduce wear, and last longer.

Unlike blends, fully synthetic oils are 100% synthetic, offering complete protection and consistent performance.

While blends are a step up from conventional motor oils, not oil synthetic, they’re still a compromise. If you want complete engine protection, especially for high-performance or daily-driven vehicles, fully synthetic is the way to go.

My Experience with Different Oil Brands

Over the years, I’ve used a range of oils from well-known brands. Many of them claimed to be “full synthetic,” but the performance and oil life didn’t match the claims. Some even required oil changes sooner than expected, and engine noise would creep in after a few thousand miles.

When I switched to AMSOIL, I noticed the difference immediately:

• Engines ran smoother and cooler
• Oil stayed clean longer
• Cold starts became easier

And best of all—I didn’t need to change oil for a full year or 20,000 miles

That kind of performance saves time and money, especially if you drive a lot or just don’t want to deal with frequent oil changes.

Not All Fully Synthetic Oils Are Equal

Here’s something most people don’t realize: some oils labeled “full synthetic” still use modified mineral oil as their base. These are called Group III base oils. They’re better than conventional, but not true synthetics.

AMSOIL uses true synthetic base stocks (Group IV and V), offering better protection, especially in extreme conditions. It’s built to outperform—not just meet—the minimum industry standards.

Why I Always Recommend AMSOIL

As someone who has tested and trusted many oils, I stick with AMSOIL for a few simple reasons:

1. It protects the engine better than anything else I’ve used
2. It reduces the need for frequent oil changes
3. It helps avoid costly repairs and keeps engines running strong for longer

Whether you drive a car, truck, motorcycle, or ATV, AMSOIL gives peace of mind by delivering real performance—not just promises on a label.

Click here to explore Amsoil products.

Is Fully Synthetic Worth It?

Yes. While it may cost more upfront, fully synthetic oil saves money over time. It reduces wear, improves fuel efficiency, and lasts far longer than blends. Plus, fewer oil changes mean less hassle and less waste.

With AMSOIL Signature Series, you can go up to 20,000 miles or one year between oil changes under normal driving conditions. That’s hard to beat.

Final Thoughts

If you’re serious about protecting your engine and getting the best value for your money, fully synthetic oil is the clear choice. And if you want the best of the best, AMSOIL delivers unmatched performance, reliability, and savings.

After years of experience with different brands, I always go back to AMSOIL—and I recommend it to anyone who wants to take better care of their vehicle.

Need help picking the right AMSOIL product for your engine?

I’m here to help. Whether you’re driving in the heat of Arizona or the cold of Canada, I can recommend exactly what your engine needs.

Read this to find why Amsoil is a superior brand!