The November 180-cst fuel oil crack to Dubai crude widened to minus $2.65 a barrel, its widest discount since October 6.
Futures fell 0.6 percent in NY, halting three sessions of gains.
Rising U.S. crude production remains an issue for OPEC as it strives to clear a global supply overhang.
Crude oil supplies from northern Iraq have fallen after the central government took control of oil fields in disputed territories from Kurdish forces.
The Organization of the Petroleum Exporting Countries (OPEC), plus Russian Federation and nine other producers have cut oil output by about 1.8 million barrels per day (bpd) since January. OPEC is said to be working on an exit strategy in an effort to reassure investors that the group will manage a controlled release of supplies to avoid a new glut when the curbs eventually expire. In early trading on Friday, Brent crude was priced above US$59 with WTI holding close to US$53 a barrel.
USA benchmark West Texas Intermediate crude rose 2.5 percent to $53.98 after closing Thursday at $52.64. The global benchmark crude traded at a premium of $6.26 to WTI, the widest in more than four weeks.
Meanwhile, analysts and investors are looking ahead to monthly US supply and demand data, out on Tuesday.
Oil prices have moved higher this week on speculation that the Organization of the Petroleum Exporting Countries (OPEC) will agree to extend a deal to cut levels of production in order to rebalance the market. "Initially, it was thought to be related to the hurricane, but to me it's becoming a little more structural".
Fuel oil stocks in the Amsterdam-Rotterdam-Antwerp (ARA) oil hub rose 6 percent, or 77,000 tonnes, to 1.334 million tonnes in the week to October 26, PJK data showed.
Gasoline stockpiles dropped by 5.5 million barrels for the week, while distillate stockpiles fell 5.2 million barrels, according to the EIA. Between February 11, 2016, and October 26, 2017, U.S. crude oil futures have approximately doubled while implied volatility has fallen ~68%. "If you have strong products demand, that means refineries are going to buy more crude oil to create those products". US oil exports, according to an emailed market report from S&P Global Platts, have "exploded" since late September and put more oil on the global market, offsetting some of the inventory build.
Compared to last year, ARA fuel oil inventories are up 122 percent and are well above the five-year average of 793,000 tonnes for this time of year.