Benchmark crude rose 93 cents to $89.84 per barrel in morning trading in New York. Earlier, oil topped $90 for the first time since Oct. 22.
An index measuring manufacturing in China showed expansion in November for the first time in 13 months. China is the world's second-largest economy after the U.S. and a huge consumer of oil. A better economy there suggests that energy consumption is likely to grow, pushing oil prices higher.
Also Monday, Greece revealed plans to spend up to $13 billion in a bond buyback program it hopes will help stabilize its mountainous debt.