Making automotive gear oil  

Challenge: Formulators creating axle and transmission fluids for heavy-duty vehicles must achieve a delicate balance: reduce emissions by improving fuel economy through lower viscosity while maintaining – and even improving – fluid durability and wear protection. Oil drain intervals have evolved from 100K KM to the 300K-500K KM range and up to 750K KM, with targets now set at 1M KM. Achieving these goals is especially difficult for heavy-duty vehicles, which must cope with higher shear, loads and pressure, which can lead to higher wear rate compared to passenger vehicles. 

How we can help: By using high-performance synthetic base stocks, innovative lubricant formulators can meet the demand for lower viscosity – currently 15-25 cSt kinematic viscosity (KV) @ 100°C but trending to 10 cSt and even lower – to boost energy efficiency, without sacrificing performance and durability. Through high viscosity index (VI), our advanced synthetic base stocks can help enhance:

  • Energy efficiency for improved fuel economy
  • Low-temperature performance
  • Shear stability for long drain intervals
  • Oxidative stability even at high temperatures
  • Wear protection for long gear life 



Synthetic solutions

In extensive testing and years of use in the field in finished lubricants, our advanced synthetic base stocks have demonstrated performance superior to mineral-oil base stocks.

Energy efficiency  

Lower coefficient of friction can help improve energy efficiency. In FZG-FVA 345 efficiency tests, low-viscosity SpectraSyn™ 4 conventional polyalphaolefin (cPAO) demonstrated lower coefficient of friction compared to Group II/II+ and Group III mineral base stocks. All three base stocks were blended roughly the same at KV 100°C.

Energy efficiency chart for AGO by blend

In mini-traction machine (MTM) testing measuring traction coefficient, a synthetic blend of SpectraSyn 4 cPAO and SpectraSyn Elite 150 mPAO demonstrated improved performance compared to blends using Group II/II+ and Group III. Better traction coefficient can help improve energy efficiency. The Group II (EHC 50), SpectraSyn™ 4 PAO and SpectraSyn Elite™ 150 blend produced similar traction coefficient as the Group III base oil blend to meet different lubrication formulations and requirements. (All blends have similar KV 100°C viscosity, Load 75N, speed 2 m/s, SRR 0-70%.)

Energy efficiency chart for AGO at a constant temparature

Low temperature performance  

This chart shows the basic properties of three SAE 75W-90 gear oils – one made using SpectraSyn Elite™ 150, one using SpectraSyn Elite™ 65 and one using SpectraSyn™ 100. All the other components in the blends are the same. The Brookfield viscosity numbers at -40° C (ASTM D2893 test) show outstanding low-temperature performance capabilities.

low temperature performance chart

shear stability chart

Shear stability  

Shear stability is taking on greater importance because of increased use of wide-span multigrade lubricants to improve fuel economy and service life. Because automotive gear lubricants typically contain viscosity modifiers that can shear in service, reducing viscosity and potentially leading to increased wear, stay-in-grade performance is part of the SAE J306 standard. The three fully synthetic formulations in this chart do not contain polymers, but the high molecular weight PAO can suffer from shear. We can see that all three blends are very shear stable, remaining within the SAE 75W-90 spec even at extended test hours. These results demonstrate long lubricant life.

Oxidative stability  

Extending drain intervals is increasingly important for commercial vehicles even as heavy-duty applications operate at higher temperatures. Base stocks that can provide improved oxidative stability help finished lubricants last longer and perform better in extreme conditions. In ExxonMobil tests, formulated oils using both SpectraSyn Elite™ mPAO and SpectraSyn™ PAO showed good performance. SpectraSyn Elite™ 65 and 150 provided superior performance.

oxidation stability chart


Market trends

Lowering CO2 emissions has become the top priority in today’s automotive gear oil marketplace. Formulators must satisfy their customers’ needs to minimize emissions through enhanced fuel economy while maintaining wear protection. That’s why we’re seeing a trend toward using synthetic base oils.

AGO annual growth forcast from Kline & Co.

Inside insights

Explore ways we can help your business.

  • ExxonMobil Chemical Lubricants formulation

    Suite of solutions

    Explore the formulation and performance advantages provided by our suite of advanced synthetic base stocks.

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  • ExxonMobil Chemical plant in Baytown, Texas

    Investing in reliable supply

    Through significant investment in global synthetic base stock capacity expansion, we can deliver what you need where and when you need it.

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  • Synovation video - Volatility

    Discover how synthetic base stocks are more able to resist evaporation and degradation due to high temperatures than mineral-based oils.

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Find the answers you need in our library of informative case studies, white papers, factsheets and more.

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Browse products 

Broad portfolio of synthetic base stocks

  • Industrial Mining Shovel with Graphics

    SpectraSyn Elite™ mPAO

    High-viscosity metallocene polyalphaolefin base stock provides high performance at a wide temperature range and exceptional low-temperature properties.

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  • traffic on highway

    SpectraSyn Plus™ PAO

    Advanced low-viscosity synthetic base stock for low volatility and low-temperature fluidity to produce advanced lubricants.

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  • truck taking turn with rolling shutter

    SpectraSyn™ Hi Vis PAO

    High viscosity base stock especially suited for industrial oils requiring high stability under harsh operating conditions.

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  • Cars going through intersection with running shutter

    SpectraSyn™ Low Vis PAO

    Low viscosity base stock offering low-temperature fluidity, low volatility and improved thermal stability.

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  • Industrial Rotary Screw with highlighting

    Synesstic™ AN

    Alkylated naphthalene base stock often used as blend component for additive solvency, seal compatibility and hydrolytic stability.

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  • Airplane taking off at night

    Esterex™ esters

    Organic esters are well-suited as a blend component for additive solvency, seal compatibility or biodegradability.

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