US base oils and lube output fell in August to its lowest since early 2021, when damage caused by an arctic storm forced the shutdown of a raft of refineries for repair work.

There was no such weather-related damage this time.

The size and speed of the drop in output in August instead matched the impact of a significant plant shutdown rather than a partial shutdown or refinery run cuts.

Base oils and lube output of 4.05mn bl (570,000t) in August fell by 23pc from 5.10mn bl the previous month to the lowest since February 2021, according to the EIA.

Base oils output had mostly held in a 4.50-5.50mn bl/month range since March 2021, even with plant maintenance work taking place during that period.

The size and speed of the drop in base oils and lube output in August far exceeded the month-on-month changes in supply during the previous 17 months and fell far below the range it had held in.

The drop in output was concentrated in the Texas Gulf coast refining district.

Its paraffinic base oils output of 1.08mn bl in August fell from 1.68mn bl the previous month to the lowest since March 2021. That was when several refineries were still recovering from the artic storm in February 2021.

Before August, its output had averaged 1.69mn bl/month since April 2021.

The sharp dip in output overshadowed a more widely-anticipated drop in paraffinic base oils and lube output in the US West coast in August to just 8,000bl.

The volume was the lowest in more than five years and coincided with scheduled plant maintenance work in the region.

The price impact of the slump in base oils output was limited.

US base oils prices remained under pressure amid sufficient supply and waning demand, especially in overseas markets.

Refiners in the US Gulf coast region also benefited from an unusually quiet Atlantic hurricane season.

The lack of any other unexpected production issues helped to cushion the impact of the slowdown in production in August.