American oil and gas giant ExxonMobil has completed an expansion at its Singapore refinery in Jurong to upgrade the production of its proprietary EHC Group II base stocks, it said in a media statement on Wednesday night.

Base stocks or base oils are used commonly for blending finished lubricants used to oil engines in vehicles, ships, planes and industrial plants. They are produced from refining crude oil.

The expansion will enable customers to blend lubricants that satisfy more stringent specifications, help lower emissions, improve fuel economy and low-temperature performance, ExxonMobil said.

Supply to customers is expected in the third quarter of this year.

Construction of the expansion started in 2017 and was completed safely and on schedule with one million workforce hours. At peak construction, more than 300 workers were employed.

ExxonMobil also has an ongoing multibillion-dollar expansion at the Singapore integrated manufacturing complex, with operations set to start in 2023. Under this investment, the expanded facilities will enable the company to convert fuel oil and other bottom-of-the-barrel crude products into higher-value lube base stocks and distillates.

ExxonMobil expects the project to significantly increase the earnings potential of the integrated manufacturing complex and chemical products.

"This successful expansion and the upcoming investment will boost our Singapore integrated complex's competitiveness significantly, and position our strong manufacturing base here for future growth of the business in the region and beyond," said Mr Gan Seow Kee, chairman and managing director of ExxonMobil Asia Pacific.

The Singapore facility is ExxonMobil's largest global integrated refining and petrochemical complex.

Separately, another oil company also recently expanded its Singapore refinery. Shell last week increased its Bukom storage capacity by nearly 1.3 million barrels, by building two large crude oil tanks.