Australia's consumer watchdog alleges fuel sold at several service stations in Queensland did not contain the additives Mobil advertised and claimed would provide engine protection.

The Australian Competition and Consumer Commission (ACCC) filed legal proceedings in the Federal Court on Tuesday against Mobil Oil Australia for making false or misleading claims about the fuel sold.

The ACCC claims Mobil displayed signs and posters at six service stations in central and north Queensland advertising fuel as 'Mobil Synergy' fuel between August 2020 and July this year.

The fuel contains additives which provide additional benefits compared with regular petrol, such as protecting engines from corrosion and better milage.

However, the ACCC alleges Mobil did not actually supply the product at those service stations.

"Consumers have no way of verifying claims made about the fuel they put into their tank and rely on the accuracy of claims made by the fuel supplier," ACCC Commissioner Liza Carver said.

"If they had known the claims made by Mobil were not correct, some consumers might have filled up their vehicles elsewhere."

The fuel sites were in Rasmussen, Yeppoon, Barcaldine, Rural View, Proserpine and Aitkenvale.

A Mobil spokesperson said the company had co-operated with the ACCC during the investigation and regretted that the incident occurred.

"This conduct, which is isolated to six sites representing less than one per cent of the entire Mobil branded network, occurred as a result of a number of operational difficulties, including unanticipated delays associated with the COVID-19 pandemic and related supply issues, as well as the remote location of the sites involved," it said.

The spokesperson said once the company became aware of the issue it took steps to either uninstall Synergy benefit claims on bowsers or to cover and remove the advertising.

Mobil said it was taking steps to ensure it did not engage in similar conduct in the future.