Costco Limits Motor Oil Purchases as Global Shortage Drives Prices Higher

US warehouse retailer Costco has imposed purchase limits on motor oil in response to a global shortage. A 10-quart (about 9.5-litre) Kirkland Signature full synthetic motor oil that previously retailed for 30 US dollars has been raised to 58 US dollars. Costco has also introduced a purchase cap, allowing each customer to buy only two cases per week.

Modern synthetic motor oil relies heavily on Group III base oils, and nearly 44% of US Group III base oil is imported directly from three Persian Gulf producers: Bahrain Petroleum Company, Abu Dhabi National Oil Company of the UAE, and Qatar's Pearl GTL.

The US-Iran conflict has severed the export route for these goods through the Strait of Hormuz. Pearl GTL was hit by airstrikes earlier in 2026, severely damaging its production capacity, which will be difficult to restore for at least a year. Normally, when Middle Eastern supply chains are disrupted, South Korean refiners step in to fill the gap; currently, South Korean refiners are also facing their own supply constraints. The refining industry is producing more diesel and jet fuel because of profit margins, which have reached their highest level in 40 years, while motor oil, diesel and jet fuel are all derived from the same batch of crude oil.

For ordinary US motorists, modern engines are sensitive to chemical composition, and automakers require motor oil to undergo strict chemical testing and certification to prevent serious failures and meet stringent environmental standards. This process typically requires oil suppliers to pay high certification fees. With crude oil prices elevated and refining capacity insufficient, cost pressures on motor oil suppliers are rising. Consumers face growing difficulty obtaining certified motor oil and alternatives, affecting vehicle maintenance.