Inadequate gas quality can impact your car’s ability to pass a smog ... “Sam’s Club fuel lacks the higher-quality additives in Top Tier brands. Regular use may result in engine-related issues,” Dillan ...

Gas prices at Sam's Club and Costco are often the same, or only slightly different, but Costco has higher quality gas. Costco ...

Costco's gas is a tier above Sam's Club Kirkland Signature ... non-TOP-TIER™ gasoline creates 19 times more engine deposits than TOP TIER™ brands after only 4,000 miles of driving.