Group III Base Stock Capacity Expansion in Texas

ExxonMobil has begun construction on an expansion of Group III base stock production at its Baytown, Texas, refinery, responding to rising demand driven by tighter emissions standards, evolving engine technologies, and the need for more resilient lubricant supply chains.

Market drivers behind Group III expansion
Lubricant formulators across automotive and industrial markets are facing increasing technical and regulatory pressure. Modern engines and equipment operate at higher temperatures, tighter tolerances, and under stricter emissions limits, requiring base stocks with greater purity, consistency, and oxidative stability.

Group III base stocks have become a critical component in meeting these requirements, particularly for high-performance passenger car engine oils and advanced industrial lubricants. Compared with lower group base stocks, Group III materials offer improved viscosity index, lower volatility, and more consistent molecular composition—attributes that support fuel efficiency, durability, and compliance with evolving specifications.

At the same time, global supply chain uncertainty has heightened the importance of reliable, regionally anchored production. For North American lubricant blenders, domestic access to Group III base stocks has become a strategic consideration rather than a logistical preference.

Scope of the Baytown refinery expansion
The Baytown Refinery Expansion Project is designed to increase ExxonMobil’s Group III base stock production capacity to approximately 8,000 barrels per day once complete. The project involves adjustments to operating rates and yields across three existing refinery units, shifting part of the production slate from gasoline toward higher-demand lubricant base stocks and diesel fuel.

Construction is currently underway, with startup targeted for 2028. By integrating new production capability within an existing large-scale refinery, the project leverages established infrastructure while rebalancing output to reflect long-term market demand.

Upon completion, ExxonMobil expects to be the only supplier globally offering the full range of base stocks from Group I through Group V, providing formulators with a single-source portfolio that spans conventional mineral oils to advanced synthetic base stocks.

Technical relevance of Group III base stocks
Group III base stocks are increasingly specified in applications beyond passenger vehicles, including agricultural machinery, marine engines, aviation ground equipment, and wind turbine gearboxes. These applications demand consistent performance across wide temperature ranges and extended service intervals.

As lubricant formulations grow more complex, the role of the base stock in enabling additive performance becomes more pronounced. The uniformity and stability of Group III base stocks support tighter formulation control and reduce variability in finished lubricants, which is particularly important for meeting OEM approvals and global performance standards.

The Baytown expansion is intended to address these formulation challenges by providing a stable, high-quality domestic supply aligned with North American demand profiles.

Positioning within a global manufacturing strategy
The Baytown project builds on a series of recent ExxonMobil investments aimed at strengthening base stock production worldwide. These include the Singapore Resid Upgrade Project and the addition of Group II base stock production at the Rotterdam refinery, both multi-year projects requiring significant engineering integration and capital investment.

Together, these initiatives reflect a coordinated approach to scaling advanced base stock capacity across key regions. Rather than incremental debottlenecking, the strategy emphasizes long-term manufacturing flexibility, portfolio breadth, and the ability to adapt production slates as lubricant and fuel markets evolve.

Application context
For lubricant formulators, access to consistent Group III base stocks underpins the ability to meet tightening emissions regulations and rising performance expectations without compromising supply reliability. The Baytown expansion illustrates how refinery-level reconfiguration and long-term capital investment are being used to align base stock production with the technical realities of modern engines and industrial equipment.

As the lubricant market continues to shift toward higher-performance formulations, large-scale, integrated production assets are likely to play an increasingly central role in stabilizing supply and supporting global product development strategies.