Three 20-litre oil containers were left at the intersection of Gray and Cameron Rds, near Papakaio, on the lower Waitaki plains, after being emptied on Wednesday night.
Wheelies were done on the site, and tyre tread was left behind.
Senior Constable Alex Wynne said the intersection, which was on a school bus route, was coated in oil and dangerous when he arrived at 7.30am yesterday.
A stock truck nearly crashed through the fence when it hit the oil and there could have been a fatal crash during the night, he said.
Staff from Whitestone Ltd were cleaning up the intersection yesterday morning and Snr Const Wynne hoped whoever responsible, if apprehended, would be billed for the clean up.
He was making inquiries to find out who was responsible.
Their actions were endangering transport and it was an offence which warranted arrest.
"We need to know who these guys are," he said.
Later in the day, Snr Const Wynne discovered a further container of oil had been spilled at the intersection of McEneany and Biggs Rds, near Pukeuri.
