No oil was spilled and no one was injured when a pup trailer rolled over on Coulson Road in Lockwood on Wednesday morning.
The trailer was being pulled by a tanker driven by Jeffrey Bokma, 24, of Billings, said Montana Highway Patrol Trooper Justin Kirchheck.
Bokma ran off the road and rolling the tanker filled with used oil after he reached for something that had fallen on the front seat, he said.
The truck was owned by Emerald Services, Inc., a Washington company.
Bokma was issued a citation for careless driving.