Motor oils that contain a large amount of viscosity index improver (VII) are typically multi-grade oils with a wide viscosity range, especially those labeled with a large difference between the “W” (cold) and high-temperature grade.
🛢️ Examples of Motor Oils High in Viscosity Index Improvers
| Motor Oil Grade | VII Content | Comments |
|---|---|---|
| 0W-40 | Very High | Widely used in high-performance engines; must flow in extreme cold and stay stable in heat |
| 5W-40 | High | Common in diesel and turbocharged engines; balances cold flow and heat resistance |
| 10W-60 | Very High | Used in racing or high-stress engines; very wide viscosity range |
| 5W-50 | Very High | Synthetic oils for sports cars or extreme temperature ranges |
| 0W-20 / 0W-16 | Moderate to High | Thin oils with some VII to ensure cold start performance and fuel economy |
🧪 Why These Oils Need More VII
Viscosity index improvers are polymeric additives that reduce how much oil thins out as temperature increases. They are essential in:
- Wide-span multigrade oils: e.g., 0W-40 spans cold and hot conditions
- Synthetic oils: which naturally have high VIs but may still use VIIs for extra range
- Fuel-efficient oils: like 0W-16 or 0W-20, where cold start and low friction are key
⚠️ Considerations
| Issue | Detail |
|---|---|
| Shear Stability | High amounts of VII can shear down over time in severe conditions (especially with poor-quality additives) |
| Cost | High-VII oils are generally more expensive |
| Base Oil Compatibility | Synthetic base oils require less VII for the same effect compared to mineral oils |
Motor oils with wide viscosity spans—like 0W-40, 5W-50, or 10W-60—contain high levels of viscosity index improvers to maintain performance across extreme temperature ranges.
Would you like help choosing a VII type (e.g., PMA, OCP, styrene-butadiene) for your formulation?
Multigrade engine oils contain large amounts of viscosity index improvers
The role and use of viscosity index improvers in engine oil
In car maintenance, choosing the right engine oil is an important part of keeping your engine running well. The main components of engine oil include base oil, additives and viscosity index improvers, etc., which work together to ensure the normal operation of the engine. This article will focus on the role of viscosity index improvers in engine oil and their uses.
Viscosity index improver is an additive mainly used to adjust the viscosity characteristics of engine oil. Engine oil viscosity is critical to the normal operation of the engine. Too high or too low viscosity may affect engine performance and life. Viscosity index improvers can improve the fluidity of engine oil at high temperatures and loads, making it better suited to the needs of the engine.
For engine oils containing a large amount of viscosity index improvers, their characteristics are mainly reflected in the following aspects:
Good high-temperature fluidity: Viscosity index improvers can improve the fluidity of engine oil at high temperatures, allowing the oil to maintain smooth flow when the engine is running at high temperatures, thus ensuring good lubrication effects.
Enhance antioxidant properties: Viscosity index improvers can also enhance the antioxidant properties of engine oil, making it less likely to deteriorate under engine high temperature and high pressure conditions and extending the service life of the engine oil.
Excellent anti-wear protection: Viscosity index improvers can form an oil film to protect the surface of engine components, reduce wear, and increase engine efficiency and life.
Using engine oil containing a large amount of viscosity index improver has many benefits, such as improving engine performance, extending engine life, reducing maintenance costs, etc. However, during use, you also need to pay attention to the following issues:
Choose the appropriate engine oil according to the requirements of the car model and engine: Different car models and engines have different oil requirements. You should choose an engine oil that meets the requirements to avoid unnecessary damage.
Follow the change cycle: Change the oil on time to ensure that the oil is working at its best. Long-term use of deteriorated engine oil may cause damage to the engine.
Avoid mixing different brands and types of motor oil: Different brands and types of motor oil may contain different additives and formulations, and mixing them may affect the performance and life of the oil.
In short, viscosity index improvers play an important role in engine oil. They can improve the viscosity characteristics of engine oil and make it better adapt to the needs of the engine. When choosing an engine oil containing a large amount of viscosity index improver, you need to pay attention to the selection according to the requirements of the car model and engine, and follow the replacement cycle to give full play to its advantages and protect the good operation of the engine.