Traffic was backed up on the 101 Freeway just west of the 405 Sunday morning, according to the California Highway Patrol, which issued a Sig Alert for over three hours.
A motorcycle crash left an oil slick on the eastbound freeway, necessitating the closure, a California Highway Patrol spokesman said.
Crews were cleaning up the oil from the freeway, but a substance used to clean the road caused another slick on both sides of the 101, and the left two lanes of both sides of the freeway were closed.
Traffic was backed up in both directions.
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All lanes reopened just before noon, according to the CHP.
The City News Service contributed to this report.