Costco has raised the price of its Kirkland Signature full-synthetic motor oil and is now limiting how much customers can buy each week. The 5-quart two-pack, which was priced at about $30 last year, now costs approximately $58. Additionally, Costco has restricted purchases of this product to two boxes per customer per week. The company has also imposed a limit on the purchase of Mobil 1's full-synthetic motor oil 1-quart six pack, capping it at five per membership. Costco has not yet responded to inquiries about these changes. The increase in motor oil prices is tied to the rising cost of crude oil, which has been affected by ongoing tensions in the Middle East. Modern synthetic motor oil relies heavily on Group III base oils, which are primarily refined from crude oil. The United States imports over 40% of these oils from the Middle East, a region that has seen supply disruptions due to the Iran war. On Monday, the price of a barrel of Brent crude oil exceeded $109, a significant jump from less than $72 in early July. This increase is partly due to an attack on a key Saudi oil pipeline, which will be out of service for weeks, limiting Saudi Arabia’s ability to redirect oil exports away from the Persian Gulf. Higher crude oil prices have also led to a rise in gasoline and diesel prices across the United States. According to AAA, the average cost of a gallon of regular gasoline has climbed to nearly $4.32, up from $4.08 a month ago and $3.18 a year ago. Meanwhile, diesel prices have hit new record highs, averaging $6.23 a gallon on Monday, up from $5.90 a week earlier. These increases reflect the close relationship between crude oil prices and the cost of refined petroleum products at the pump. As oil prices continue to climb, oil companies may shift their focus from producing motor oil to refining more diesel and gasoline. This is because there is significantly higher global demand for diesel and gasoline, with much larger daily volumes compared to motor oil. With this shift, it remains unclear whether other motor oil retailers like Walmart, Amazon, and AutoZone will follow Costco’s lead in raising prices or imposing purchase limits. So far, these companies have not responded to requests for comment.