The Deer Park refinery, a joint venture of Shell Oil and Pemex, is to restart five units involved in producing motor fuel.
The refinery is restarting the hydroprocessing unit, coker, gas oil hydrotreater, catalytic reformer and platformer, according to Reuters.
A hydroprocessing unit uses hydrogen to increase the amount of motor fuel made from a barrel of crude oil, in particular, cheaper heavy, sour crude and reduces sulphur pollution.
The gas oil hydrotreater uses hydrogen to reduce sulphur in gas oil used in the refinery's gasoline-producing catalytic cracking unit.
The catalytic reformer and the platformer create high-octane blending components for petrol.
A coking unit increases the amount of motor fuel from crude oil, converting the gunky residue at the bottom of a barrel of crude into petroleum coke, a coal substitute.
The restart could last through to 17 February 2010, according to a notice filed with the Texas Commission on Environmental Quality.