We had a similar thing here too. When Challenge opened, they were getting petrol from singapore as well. But then shell bought them, and now they use the rubbish made at the marsden point refinery. Pump gas here is complete and utter sh!t. Some companys sell so called 98 octane, but it's not availble in the south Island yet.
The fine for using leaded gas on the street is ten grand, and it's not cheap either.

(sorry to go off topic, but this is a sore spot for me. When we lost leaded gas, cars that ran sweet turned into pigs overnight)