Costco has raised the price of its Kirkland Signature full-synthetic motor oil and begun limiting how much any one member can purchase, as a global lubricant shortage tied to the ongoing Middle East conflict pushes crude oil toward $100 a barrel.
That 10-quart case — two 5-quart bottles, enough for a typical V6 or V8 oil change — has jumped to $57.99, compared with the roughly $30 price members had grown accustomed to paying, according to The Drive. Stores are capping purchases at two units per customer per week. The retailer has also imposed a five-per-member limit on Mobil 1, with six quarts of that brand running $44.
The rationing reflects pressure from multiple directions. The connection to fuel prices runs through the refinery: base oil shares its crude-oil origins with gasoline and diesel, so when margins on finished fuel are strong, refiners have a financial reason to favor fuel production over lubricant stock, according to The Auto Wire. EIA data showed the gasoline crack spread sitting roughly a dollar per gallon higher than where it stood at the same point in 2025, a gap that has squeezed base oil availability and pushed its price upward.
Regulatory and licensing costs add a separate layer of expense. The Kirkland 5W-30 displays the dexos1 Gen 3 certification, GM’s proprietary specification, and earning that mark is not free — manufacturers must put their formulation through GM’s independent testing protocol and obtain a license from the automaker, paying separately for each product and each unit sold, according to The Auto Wire. Layered on top of that is an industry-wide burden: when the API SP category took effect around 2020, it introduced seven additional laboratory tests with no equivalent in the previous standard, among them a procedure targeting low-speed pre-ignition, the knock-like detonation problem associated with modern turbocharged, direct-injection engines.
The supply squeeze is unfolding against a backdrop of a worsening global oil deficit. The International Energy Agency cut its 2026 global oil supply forecast to 102 million barrels per day in August, projecting a deficit of 1.8 million barrels per day in the third quarter — more than double its prior estimate. Cumulative global inventory draws since the start of the U.S.-Iran conflict have reached more than 500 million barrels, and Chevron CEO Mike Wirth said last week that the cushions that had softened earlier price increases have been exhausted. U.S. diesel prices crossed $6 per gallon for the first time, sitting at $6.06 as of Monday, an 8-cent increase from Sunday and 21 cents above week-earlier levels, according to AAA.