Costco has raised the price of its Kirkland Signature full-synthetic motor oil to $57.99 for a 10-quart case, from roughly $30, and capped purchases at two units per member per week. The retailer has also limited Mobil 1 purchases to five units, with six quarts priced at $44. The restrictions come as a Middle East conflict contributes to a global lubricant shortage and pushes crude oil toward $100 a barrel. Base oil competes with gasoline and diesel for refinery capacity, while stronger fuel margins have reduced incentives to produce lubricants. EIA data showed the gasoline crack spread about $1 per gallon above its level at the same point in 2025. Certification and testing requirements, including GM's dexos1 Gen 3 license and the API SP category's seven additional laboratory tests, add to costs. The International Energy Agency has forecast a 1.8 million-barrel-per-day oil deficit in the third quarter and cut its 2026 supply forecast to 102 million barrels per day. Global inventories have fallen by more than 500 million barrels since the start of the U.S.-Iran conflict, while U.S. diesel prices reached $6.06 per gallon. At current Kirkland prices, changing oil at home now costs roughly what an independent repair shop charges, according to The Auto Wire.