Top Tier Gas
As described at www.toptiergas.com:
"TOP TIER Detergent Gasoline is the premier standard for gasoline performance. Six of the world's top automaker, BMW, General Motors, Honda, Toyota, Volkswagen and Audi recognize that the current EPA minimum detergent requirements do not go far enough to ensure optimal engine performance.
Since the minimum additive performance standards were first established by EPA in 1995, most gasoline marketers have actually reduced the concentration level of detergent additive in their gasoline by up to 50%. As a result, the ability of a vehicle to maintain stringent Tier 2 emission standards have been hampered, leading to engine deposits which can have a big impact on in-use emissions and driver satisfaction.
These automakers have raised the bar. TOP TIER Detergent Gasoline help drivers avoid lower quality gasoline which can leave deposits on critical engine parts, which reduces engine performance. That's something both drivers and automakers want to avoid."
"Currently, many gasoline retailers provide fuels with lower-quality additive packages that can build up deposits on fuel injectors and on intake valves. Others can build up deposits in the combustion chamber and may lead to intake valve sticking. These lower levels of additives can have negative impacts on engine performance and vehicle responsiveness."
"Gasoline retailers must meet the high TOP TIER standards with all grades of gasoline to be approved by the automakers as providing TOP TIER Detergent Gasoline."
The retailers known to be on the TOP TIER list that have a presence in the Pacific Northwest area are: