What’s the difference between the “Top Tier” designation I’ve seen and Tier 3?
Tier 3 and the “Top Tier” trademark are very different! Tier 3 gas protects air quality, while “Top Tier” is meant to protect engine health.
Tier 3 gasoline standards are set by an EPA rule and concern gasoline sulfur content. Using Tier 3 gas results in fewer harmful emissions (NOx and VOC—important precursors to both PM2.5 and ozone pollution) and affects air quality. It is regulated by the EPA.
"Top Tier" are industry performance standards and trademarks designed and supported by a set of major automakers related to gasoline detergent content. According to industry spokespeople, using "Top Tier" gas results in less engine 'gunk' build-up and improved engine life. It is privately regulated.
Why aren’t all stations selling Tier 3 gas?
Of the six major refineries that produce gas that is sold in the area, only four comply with EPA Tier 3 regulations by making and selling gas at Tier 3 sulfur levels locally—the others either purchase credits or comply by corporate pooling.
Some gas station brands or locations get their gas from refineries which meet standards locally, others don’t. For example, Sinclair stations will always carry gas from the clean-producing Sinclair refinery—same with Speedway stations and the Marathon refinery. The gas sold by some stations is a mix, so there’s no way to know for sure, and still others will buy whatever is cheapest, so it won’t be reliably Tier 3.
Will I see signs at the gas station telling me what gas is Tier 3?
Probably not—at least not yet! Some brands may elect to carry signs that highlight their efforts (for example, Chevron’s “Commitment to Utah” signs that appear at pumps), but there is no required or regulated signage. When in doubt, look for the brand logos highlighted here.
Does Tier 3 gas come from different pumps?
No. Tier 3 doesn’t affect fuel efficiency or engine performance; it is much the same as the gas you’ve been using, it just has less sulfur. For a more technical answer, you can read the EPA’s test results.