Costco is a wonderful company. They test toilet paper like there is no tomorrow. I believe the batteries they sell under their name are Duracell batteries.
I have watched videos about the Amazon and Walmart oil they both tested fairly well. They are mid-tier products with a good additive package, so I'm sure the Costco oil is just fine.
I personally like Pennzoil Platinum I believe it is one of the best oils out there especially for the price.
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