While Amsoil certainly produces excellent motor oil, it makes the lowest rung on this ranking due to its limited product line. The brand's products can be ordered via the Amsoil online store.

Let’s explain all of those confusing numbers, letters and terms to help you choose the right oil for your car.

Those shopping at Costco may have encountered the chain’s exclusive Kirkland Signature Synthetic Motor Oil and wondered how it compares to some of the best motor oil brands. While the brand is ...