Is Costco's Kirkland Brand Motor Oil Any Good, And Who Makes It?

Gaining a good understanding of your car's motor oil is crucial to ensuring it runs properly. If you're a Costco member, you may have come across the chain's exclusive Kirkland Signature Synthetic Motor Oil and wondered how it stacks up to some of the best motor oil brands out there such as Mobil and Valvoline. Having only been widely available on the market for the last four years or so and coming in at an oddly low price, it's easy to be suspicious of its performance. But given Costco's reputation for sporting high-quality brands without the fancy marketing of its competitors, it shouldn't come as a surprise that this efficient and economical choice has been mostly well-received by users. 

Available in SAE 5W-30, SAE 5W-20, and SAE OW-20 viscosities, the synthetic oil claims to provide effective protection to your engine while also controlling thermal breakdown. It's been able to meet oil standards set by API SN Plus and ILSAC GF-5 and the viscosity specifications of the Society of Automotive Engineers when set under varying temperatures, meaning it is designed to allow for maximum fuel efficiency and engine protection. 

Ultimately, as long as you don't skip on regular oil maintenance, this brand is great for a wide range of vehicles from older cars to gas trucks. However, due to its limited oil range, it's not the best fit for Diesels or high-performance vehicles, which often require more specific and high-class oils. 

While Costco is the primary retailer of Kirkland Signature Synthetic Motor Oil, it is not its manufacturer. Like all Kirkland products, the motor oil is instead farmed out to a separate manufacturer before being put on store shelves. That distinction belongs to Warren Oil. While Warren carries a handful of its own retail brands such as Gold Brand and Lubriguard, it is most well known for providing a wide range of greases, lubricants, and chemicals to various retailers. 

When looking at Kirkland Motor Oil, the brands it is most comparable to are Walmart's Super Tech and Amazon Basics Synthetic Motor Oil, both of which are also manufactured by Warren Oil. These oils meet similar specifications and standards from across the industry while also performing well in a variety of tests. The trusted YouTube channel Project Farm pitted Kirkland against Super Tech in a series of extensive and rigorous tests for evaporation loss speed, cold temperature flow, film strength, and more. In the end, both came extremely close in every category. This shouldn't come as a surprise, as both brands come from the same manufacturer and are likely made from similar components.