New evidence of surging U.S. oil supplies sent prices on a roller-coaster ride Thursday, reflecting the growing divide among traders over whether an eight-month rout is over.

The U.S. Energy Information Administration said oil inventories grew by 7.7 million barrels in the week ended Feb. 13. Analysts said swelling stockpiles are a sign that producers aren’t cutting back on output despite a more than 50% collapse in prices since last summer. In its report, the EIA said U.S. oil production was on track to reach a 42-year high...