Oil refiner and marketer Sunoco Inc. (SUN) reported weaker-than-expected third quarter results as its refining and chemicals operations slipped in the red, pulled down by reduced margins and production. Loss per share, excluding special items, came in at 29 cents, significantly wider than the Zacks Consensus Estimate of 9 cents. In the year-ago period, the Pennsylvania-based company earned $4.78 per share. Revenues were down 42.6% year over year to $8.7 billion.   Refining & Supply   The Refining & Supply segment lost $118 million during the quarter, as against a profit of $398 million in the year-earlier period, mainly on account of lower realized margins and lower production volumes, partly canceled by lower expenses. Realized margin averaged $2.72 per barrel, down 81.7% from the third quarter of 2008, reflecting a very weak East Coast refining margin environment. Total production was down approximately 17.2% year over year to 669.2 ...