US base oils and lube output fell in April amid a slump in production in the West Coast region.

Total base oils and lube output of 4.89mn bl in April fell by 5pc from 5.13mn bl the previous month, according to the EIA. The volume was down from more typical levels of around 5.2mn bl/month over the past year.

Output slowed at a time when feedstock and diesel prices were surging faster than crude oil because of concern about increasingly tight supply. The trend incentivized refiners to maximise production of middle distillates.

The size of the drop in output in the US West Coast region suggested other factors also had an impact.

Total output in that region fell to 150,000bl in April, from an already low 333,000bl the previous month.

Within that volume, output of paraffinic base oils fell to 45,000bl. The volume was down from average levels of more than 440,000 bl/month over the past year and the lowest since 2016.

An almost complete cessation of base oils output like that typically takes place because of factors like plant maintenance work.

The slowdown in US base oils output curbed the volume of surplus supplies available for export to other markets. Some of those markets, like Europe, were facing tighter-than-expected supply and seeking additional volumes from overseas sources.