British Touring Car boss Alan Gow has hailed the championship's new mandatory breath-testing a success after all drivers and senior officials passed.
The testing, designed to ensure competitors and officials are free from the effects of alcohol in their system, will take place at every round and Oulton Park was the scene of its introduction.
All drivers will be tested ahead of each day of official running.
A 'zero tolerance' policy means any drivers or officials who fail the test will not be able to participate until they pass, but there were no issues at Oulton.
"Everyone is more than happy to do it - we've not had one complaint," Gow told AUTOSPORT.
"They all know it's the right thing to do and is a responsible message to send the public. It's driver scrutineering."
AlcoSense, which sponsors Hunter Abbott's Rob Austin Racing Audi A4, provides the breathalysers.