Costco rationing oil has started, with a two-box-per-customer weekly limit on Kirkland Signature full-synthetic motor oil and higher prices on key products. The move hits members who buy in bulk, a rare restriction for a retailer built around bigger carts and larger pack sizes.
Kirkland Signature jumps to $58
The 10-quart box of Kirkland Signature full-synthetic motor oil rose from $30 to $58, a steep reset for members who had treated the product as a routine stock-up. Costco also placed a strict two-box-per-customer weekly limit on that item, turning a warehouse staple into a rationed purchase.
That change is the clearest sign that supply is tight enough to reach the shelf. Costco is not trimming an optional add-on; it is limiting a product category tied to maintenance, where buyers usually expect to leave with several boxes at once.
Mobil 1 capped at five
A six-quart case of Mobil 1 is priced at $44, and Costco has capped purchases at five per member. For shoppers who split purchases across vehicles or try to buy ahead, the ceiling means the store will no longer function as an unlimited source for one trip.
General Motors requires vendors to pay double licensing fees to print the Dexos-approved badge on packaging, and Costco’s Kirkland brand shows that certification. The label signals compatibility standards, but the bigger issue for members is availability: the product is still on sale, just with tighter limits and a higher bill at checkout.
Group III supply tightened
44% of the United States Group III supply is imported directly from Bapco, ADNOC, and Pearl GTL, and modern synthetic motor oil relies heavily on Group III base oils. That supply chain has been squeezed by the ongoing military entanglement with Iran and the blockade of the Strait of Hormuz, which have choked off exports.
March 2026 damage to The Pearl GTL facility in Qatar added another layer of pressure, while South Korean refiners are struggling to secure raw crude oil. Motor oil, diesel, and aviation fuel all originate from the same barrels of raw crude, and global profit margins for diesel and jet fuel have hit 40-year highs, pulling feedstock toward the products with the strongest economics.
For Costco members, the practical takeaway is simple: buy only what you need within the weekly cap, expect the higher shelf price to hold until supply improves, and do not assume the rationing will disappear quickly. Costco has started rationing motor oil because the chain behind it is still under strain, and the checkout limit is now part of that strain.
