The collaboration builds on the launch of BYD–Mobil hybrid-specific engine oils, designed for DM-i PHEVs operating under frequent start-stop and low-temperature conditions.
On January 26, BYD signed a long-term strategic cooperation memorandum of understanding with ExxonMobil (China) Investment Co. at BYD’s headquarters in Shenzhen.
Under the agreement, the two companies will focus on customized product development, technical collaboration and joint standard-setting related to plug-in hybrid electric vehicles (PHEVs), while also exploring the application potential of new materials in hybrid powertrain systems.
The partnership builds on existing cooperation between the two sides.
In December last year, BYD and ExxonMobil China jointly launched a dedicated engine oil designed specifically for PHEVs, branded as the BYD–Mobil hybrid-specific series.
The product was tailored for BYD’s DM-i dual-mode hybrid technology, addressing the differentiated lubrication demands of plug-in hybrids operating under frequent start-stop conditions, short-distance low-temperature driving and intermittent high-load scenarios.
Although BYD ceased production of pure internal combustion engine vehicles in March 2022, PHEVs under the current technological pathway still rely on engine systems.
Compared with conventional fuel vehicles, PHEV engines do not operate continuously.
Instead, they experience more frequent start-stop cycles and fragmented operating periods, placing higher requirements on engine oil performance in terms of wear resistance, moisture control and stability.
Taking the 0W-20 ultra-high-grade oil in the series as an example, its anti-wear performance exceeds industry standards by more than 50%, significantly reducing engine wear caused by frequent start-stop operation.
In terms of moisture management, the product’s emulsion stability reaches 2.5 times the standard level, enabling targeted optimization for moisture accumulation issues commonly seen in PHEV engines under short-distance and low-temperature conditions.
Beyond technical collaboration, supply chain coordination is another key pillar of the partnership.
Leveraging its global production and logistics network, ExxonMobil will support BYD’s overseas plants with lubricants compliant with local regulations, while jointly optimizing supply processes.
Data show that BYD sold a total of 4.6024 million NEVs in 2025, including 2.2567 million BEVs and 2.2887 million PHEVs, with plug-in hybrids accounting for nearly half of total NEV sales.
The Song Plus series, marketed overseas as the Seal U, is not only a core volume driver within BYD’s lineup but also became the best-selling PHEV model in the European market in 2025.
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