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Group IV vs Group V base oils: what’s the difference?
If you’ve ever wondered what makes premium synthetic motor oils like AMSOIL perform so well, it comes down to what’s inside, and that starts with the base oils.
Among the most advanced are Group IV and Group V base oils, which form the foundation of top-tier synthetic lubricants.
While both are synthetic, there are critical differences between them that affect performance, protection, and longevity.
Group IV base oils are made from polyalphaolefins (PAO), chemically engineered molecules built for consistency and purity.
They’re designed to:
Because they’re free of impurities and offer excellent molecular uniformity, PAO-based oils resist breakdown better than traditional mineral oils and even some synthetic blends.
You’ll often find PAO oils in high-performance full synthetics like AMSOIL Signature Series.
Group V base oils are a broader category that includes non-PAO synthetics, such as esters, alkylated naphthalenes, and other specialty fluids. Esters, in particular, offer some major benefits:
Esters also carry a slight electrical polarity, allowing them to cling better to metal surfaces, providing superior startup protection and reducing friction.
While both are fully synthetic, here’s what sets them apart:
High-end oils like AMSOIL often use a blend of both Group IV and Group V for the perfect balance of performance, stability, and engine cleanliness.
Choosing oil made with Group IV or V base oils means:
If you’re pushing your vehicle hard—or just want the best protection with fewer maintenance headaches—PAO- and ester-based oils are the way to go.
AMSOIL formulates with these advanced base oils to ensure your engine stays protected whether you’re driving in the cold Canadian winters or the hot highways of the southern U.S.
Not All “Full Synthetic” Oils Are Equal
Many so-called “full synthetic” oils on the market are made from Group III base oils—highly refined mineral oils. While technically synthetic by North American standards, they lack the performance advantages of Group IV and V synthetics.
That’s why AMSOIL stands out—it uses true synthetic base stocks that exceed industry requirements and deliver real-world results.
Quick Benefits of Group IV & V Oils
Whether you’re maintaining a performance car, family SUV, or work truck, oils made with Group IV and V base oils offer serious value.
Q: Is Group V better than Group IV?
Not necessarily. Group V esters offer different benefits like detergency and polarity. Most premium oils combine Group IV and V for optimal performance.
Q: Why are PAO oils better?
PAO oils resist oxidation, stay stable under pressure, and perform well across a wide temperature range.
Q: What oils use Group IV and V base oils?
AMSOIL Signature Series, racing oils, and some aerospace-grade lubricants use these advanced synthetics.
Q: Is Group III synthetic bad?Not bad, but it doesn’t match the performance and longevity of true synthetics made from Group IV and V.
The difference between Group IV and Group V base oils might seem technical.
But it plays a big role in how well your engine is protected.
Oils made from these base stocks aren’t just marketing—they’re scientifically superior.
And that’s why I always recommend AMSOIL. With its use of advanced PAO and ester blends, it offers real performance gains, less wear, and more savings in the long run.
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