ISSAQUAH, WASHINGTON / RankWire.AI / – Costco has raised the online price of its Kirkland Signature full synthetic motor oil to $57.99 for a 10-quart package. The case contains two 5-quart bottles and covers several widely used viscosity grades. Costco also placed a purchase limit on the product. Members can buy no more than two units in one transaction during a seven-day period. The restriction appears on selected Kirkland Signature motor oil listings on the retailer’s website.
The new price marks a steep increase from levels reported about a year earlier. The same quantity had sold for roughly $30 during that period. Costco now lists several Kirkland full synthetic formulations at $57.99 online, including 5W-30, 5W-20 and 0W-20. Warehouse prices can differ from online prices and may vary by location. Each package contains 10 quarts, making the change notable for customers who buy oil for routine vehicle maintenance.
Purchase restrictions also cover several Mobil 1 products sold through Costco. Mobil 1 is an ExxonMobil brand and ranks among the best-known synthetic motor oil labels in the United States. Selected six-packs of one-quart bottles now carry a limit of five units per membership. The affected listings include standard and high-mileage formulations across multiple viscosity grades. The limits therefore extend beyond Costco’s private-label motor oil and include a major national lubricant brand.
Purchase limits reach beyond Kirkland motor oil
Synthetic motor oil production depends on refined base oils and additives that meet modern engine protection standards. Group III base oils form an important part of many synthetic lubricant formulations. The United States relies on overseas suppliers for a significant portion of these materials. Producers in the Persian Gulf supply a large share of global Group III output. Recent disruptions across Middle East energy markets have tightened supplies of several petroleum products and refining inputs used throughout the lubricant industry.
Crude oil prices also remained above $100 a barrel in mid-September. Brent crude traded near $107.82 on September 16, while West Texas Intermediate stood near $104.86. Energy markets continued to reflect disruptions affecting major Middle East production and shipping routes. Traffic through the Strait of Hormuz remained well below normal levels. Saudi export infrastructure on the Red Sea also faced interruptions, adding pressure across regional petroleum supply chains.
Synthetic oil market faces broader supply pressure
Costco’s affected Kirkland products include grades used in many passenger cars, sport utility vehicles and light trucks. The retailer says the oils provide protection against wear and help control thermal breakdown. Selected formulations meet API SP and ILSAC GF-6A performance standards. Those standards cover areas such as engine cleanliness, fuel economy and protection against certain types of wear. Mobil 1 listings at Costco also include several standard, fuel-economy and high-mileage options.
Costco has not released a detailed public explanation for the higher Kirkland motor oil price or the new purchase limits. Its online listings currently show both the $57.99 price and the two-unit restriction for selected products. Separate Mobil 1 pages continue to display five-unit membership limits on several formulations. The changes arrive during a period of elevated crude prices and tighter lubricant supply, while Costco’s posted limits give members clear guidance on current availability and purchasing rules.