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.
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Traffic was backed up in both directions.
All lanes reopened just before noon, according to the CHP.
The City News Service contributed to this report.