Oil edges up ahead of U.S. data, OPEC squabbles cap gains

By Sabina Zawadzki LONDON (Reuters) - Oil edged up on Tuesday ahead of the release of U.S. crude inventory data, which in recent weeks has provided bullish surprises, but a flurry of top-level comments from OPEC members regarding chances of an output cut kept a lid on prices. U.S. West Texas Intermediate (WTI) crude futures turned positive, gaining 37 cents to $50.89 a barrel, after being negative throughout much of Asia trading. The private American Petroleum Institute is due to publish its wee