(Adds differential coming down, numbers, background)
NEW YORK, Nov 15 (Reuters) - U.S. Gulf Coast gasoline differentials spiked 3-4 cents a gallon on Friday but then quickly retreated again, traders said, following a fire at Chevron Corp's Mississippi refinery which killed one worker.
The differentials for M4 conventional gasoline were bid at 13.00 cents under December RBOB gasoline futures on the New York Mercantile Exchange, around 3.50 cents higher. They then tumbled to 17.50/16.00 cents, close to flat.
A4 gasoline, formulated for blending with 10 percent ethanol, traded at 14.00 cents under, 3.50 cents higher and was offered at 13.00 cents under. It was then heard at 16.50/18.00 cents under and at 18.50/17.00 cents under, 0.25 cent lower.
"Bet we see last night's numbers here before long, if not already," said on Gulf trader.
Gulf Coast ultra-low sulfur diesel (ULSD) actually slipped 0.75 cent a gallon to 8.75 cents under December heating oil futures while cash heating oil was flat.
A worker was killed by a fire early Friday at a cracking unit at Chevron's 330,000-barrel-per-day Pascagoula, Mississippi refinery. The refinery is by far the largest in the state, with two other minor refineries processing just 34,000 bpd.
Nevertheless, there is huge refining capacity in the neighboring Gulf Coast states that should keep supplies in the region topped up.
(Reporting by Robert Gibbons and Sabina Zawadzki; Editing by Bernadette Baum)