In theory here's the answer. I'm not familiar with Warren but there's a lot I don't know.
Kirkland Name: Kirkland Signature Full Synthetic SAE 5W-30
Kirkland Price Per Unit: $24.39*
Verdict: Confirmed
Motor oil can be a saturated market, leading many to just grab the nearest one they see and hope for the best. In reality, a lot of different brands are made by the same company. In Costco’s case, their oil is manufactured by Warren Oil. Warren also supposedly produces Amazon’s AmazonBasics motor oil. It’s confirmed in writing on the back of the jug, so we don’t need any more proof. The product sells well for Costco, which is unsurprising given the price tag. At just $24.39 for five quarts, it’s a bargain purchase that will last.
Just make sure that you don’t let it linger in your garage forever. Even motor oil has a use-by date. Once opened, motor oil should be replaced every five years, no matter how much you’ve got left in the bottle. That being said, $24.39 every few years isn’t going to break the bank.
Which Brands Are Hidden Behind Costco’s Kirkland Label? | Investing Magazine
Costco's Kirkland label is often seen as the cheaper, not-so-good version of other, big brand products. While there's something to be said for grabbing a bargain, there's a stigma attached to Kirkland that the company just can't seem to shake. However, there could be a big secret lurking behind...
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Warren Motor Oil
Kirkland Name: Kirkland Signature Full Synthetic SAE 5W-30
Kirkland Price Per Unit: $24.39*
Verdict: Confirmed
Motor oil can be a saturated market, leading many to just grab the nearest one they see and hope for the best. In reality, a lot of different brands are made by the same company. In Costco’s case, their oil is manufactured by Warren Oil. Warren also supposedly produces Amazon’s AmazonBasics motor oil. It’s confirmed in writing on the back of the jug, so we don’t need any more proof. The product sells well for Costco, which is unsurprising given the price tag. At just $24.39 for five quarts, it’s a bargain purchase that will last.
Just make sure that you don’t let it linger in your garage forever. Even motor oil has a use-by date. Once opened, motor oil should be replaced every five years, no matter how much you’ve got left in the bottle. That being said, $24.39 every few years isn’t going to break the bank.