Costco has introduced purchase restrictions on motor oil as supply disruptions from the U.S.-Iran conflict tighten availability. Members are now limited to one transaction and a maximum of two units every seven days for the retailer's Kirkland Signature full-synthetic oil.

The policy responds to rising prices and dwindling stocks. A 10-quart case of Kirkland Signature full-synthetic now costs $57.99, up sharply from the mid-$30 range in prior periods. Similar caps apply to other brands, with Mobil 1 limited to five units per member.

The shortages stem from the ongoing military conflict involving the United States, Israel, and Iran, which has disrupted shipping through the Strait of Hormuz and damaged key production facilities. Roughly 44 percent of U.S. Group III base oil supply, essential for synthetic motor oils, historically came from Persian Gulf producers. Iranian actions have curtailed these imports, while strikes on facilities like the Pearl GTL plant in Qatar have further reduced global output.

Refiners have shifted focus toward higher-margin gasoline production, squeezing lubricant supplies. This has led to broader market pressure, with reports of reduced allocations across retailers and manufacturers.

The changes affect DIY vehicle maintenance, a common cost-saving practice for many consumers. Purchase limits prevent bulk buying that previously allowed members to stock up affordably.

Costco's move aligns with reports from multiple outlets detailing the policy rollout in recent days. The restrictions highlight how geopolitical tensions in the Middle East are rippling into everyday consumer goods in the United States.