HOUSTON - Costco Wholesale Corp, which sells some of the cheapest gasoline in the country, says a revised tariff overhaul on the giant Colonial Pipeline would add to its costs of providing gasoline. The warehouse club operator told the Federal Energy Commission in a filing on Tuesday that a new tariff system proposed for the massive artery sending fuel from the U.S. Gulf Coast to the Northeast would leave it scrambling for space on the critical but clogged line. Costco is among a group of companies challenging Colonial’s rewrite of tariffs governing how space is allotted to ship barrels of gasoline and distillates on the 5,500-mile (8.851 km) system. Costco, which sells fuel at often steep discounts in order to attract customers to its stores, said Colonial’s proposed lottery system leaves too many shippers out, forcing them to find other ways to move barrels. Colonial has been full for about three years and routinely allocates space based on shipper history, or how many barrels shippers regularly move in 72 cycles each year. Those that meet a certain threshold are “regular” shippers and qualify for consistent space. Those that do not can currently attain that status by swapping their shipper histories back and forth as needed. The new tariff would largely prohibit that practice, leaving them to try to get a fraction of remaining space via a lottery. Colonial says the change would stop shippers from making history transfers that undercut rewarding shipper loyalty. Costco said it would have to win a lottery pick 75 percent of the time - in 54 of the year’s 72 cycles - to meet the threshold to qualify as a regular shipper. Otherwise, Costco would be relegated to buying unused line space from another regular shipper on top of fuel costs and Colonial’s transport fees. Line space is a secondary market that emerged as shippers grappled with the full system. Regular shippers that may not need all the space they are allotted in a cycle sell the excess - in pennies per barrel shipped - to others who need it. That allows regular shippers to maintain a consistent allotment without paying a penalty for failing to use it all - and risk Colonial shrinking it. Costco said in the past year it has bought line space to various refiners and suppliers for every gallon it took from a Colonial destination. That puts Costco at a disadvantage to its competitors that are regular shippers that do not have to buy line space, it said.