[Edaily Reporter Bang Sung Hoon ] U.S. warehouse club Costco has been embroiled in controversy after reportedly beginning to effectively “ration” engine oil. The company, which has long promoted the slogan “cheap and in large quantities,” has not only raised the price of engine oil by nearly double but has also capped the amount each member can purchase.

According to CNBC on the 14th (local time), the price of a two-pack of Costco’s private-label Kirkland Signature synthetic engine oil (5 quarts, approximately 4.7 liters) recently rose to $57.99 (78,200 won). The product, which typically cost around $30 (40,455 won), has nearly doubled in price. Costco’s website states that for this product, “purchases are limited to one per membership, with a maximum of two per 7-day period.” Costco did not immediately respond to CNBC’s request for comment.

Price hikes and purchase limits have also been observed for other engine oil brands. On the Costco website, a 6-pack of 1-quart bottles of Mobil 1 engine oil is selling for $43.99 (59,321 won), with a limit of five packs per member.

The fact that a retailer known for low prices and bulk sales has imposed purchase limits indicates just how heated the market for crude oil-derived products has become. Brent crude, the international benchmark, surpassed $109 (146,986 won) per barrel this morning, hitting its highest level since last May. This rise follows a 9% increase the previous week. West Texas Intermediate (WTI) crude also surpassed $104 (140,244 won). However, the closing prices for both grades fell to $105.68 (140,2509 won) and $101.39 (136,724 won), respectively.

The prolonged and widening conflict in the Middle East is driving up oil prices. Saudi Arabia halted operations on part of its East-West pipeline last week after a drone attack originating from Iraq damaged it.

As crude oil supplies tightened, refiners began to generate higher profits from producing finished fuels such as diesel and gasoline. Consequently, they are prioritizing fuel production over base oils—the key raw material for synthetic motor oil—using the same crude oil. This is why the supply of motor oil is shrinking further and prices are rising.

The United States relies on the Persian Gulf region for a significant portion of the Group III base oils used to produce synthetic engine oil. Automotive consulting firm Ducker Kahlil analyzed that this supply has also decreased as shipments through the Strait of Hormuz have been disrupted. According to the firm, prices at 15 major engine oil service providers—including GP Lube, Valvoline, and Take 5—rose by 6.2% between July of last year and July of this year. This exceeds the overall inflation rate.

The conflict in the Middle East is also driving up gas prices at the pump. U.S. gasoline prices hit an all-time high as of Labor Day, while diesel prices surpassed $6 (8,091 won) per gallon (approximately 3.8 liters), setting a new record.