Tier 3 fuels are here at last!

By Ashley Miller

Doing your part to improve Utah’s air just got easier thanks to Tier 3 gasoline

Over the last several years we’ve been hearing a lot about Tier 3 gasoline. It should play an important role in cleaning up air pollution coming from passenger cars and trucks. Since the new year Chevron, Marathon and Silver Eagle refineries have been making the lower-sulfur Tier 3 gasoline locally and selling it to certain retailers across the state.

Tier 3 refers to the strengthened emissions standards set by the EPA that reduce pollutants from both gasoline and vehicles. The Tier 3 gasoline standard requires petroleum refiners to reduce the sulfur content of gas from an annual average of 30ppm down to 10ppm. The Tier 3 vehicle emissions standard improves the function of catalytic converters in newer cars (model year 2017 and newer). When used together, these vehicle and gasoline standards reduce the amount of pollution coming from tailpipes by 80%.

There is a benefit for older vehicles burning Tier 3 gasoline as well. When an older car runs  on Tier 3 gasoline, the emissions coming from its tailpipe are reduced by up to 12%. Considering about half of the air pollution along the Wasatch Front comes from cars, Tier 3 is an important part of the solution.

Utah’s petroleum refiners have several methods available to comply with the Tier 3 standard. They can produce the lower-sulfur gasoline locally, they can rely on the corporate averaging across all of their facilities, or they can purchase sulfur credits. Marathon, Chevron, and Silver Eagle, three out of the five  local petroleum refineries in Utah, have made substantial investments to produce the lower-sulfur gasoline locally, rather than rely on the other methods of compliance.

Where can you buy Tier 3 gasoline today in Utah?

You won’t see any new or different button labeled “Tier 3” at the pump. But Tier 3 gasoline is what you will be getting now, at any octane level, at Speedway, Chevron, Shell, Exxon and Texaco stations across Utah. Sinclair has committed to making the lower-sulfur gasoline at its facility in Wyoming and selling it in Utah. Tier 3 sulfur content is met by an annual average, and no participating station can guarantee the sulfur content of any particular gallon of gas. However, over the course of a year, the effect should be significant.


Ashley Miller, J.D., is the vice-chair of Breathe Utah,  vice-chair of Utah’s Air Quality Policy Advisory Board and is a member of the Salt Lake County Environmental Quality Advisory Commission.


An up-to-date list of participating stations

Additional gas stations are always being added. Representative Suzanne Harrison recently launched a new website that will help Utahns find out where to fill up with Tier 3 gasoline:


How to tell if yours is a Tier 3 vehicle

The first Tier 3 makes and models started with model year 2017. By now, most new cars and trucks are Tier 3. But the easiest way to tell if a car is Tier 3 is to pop the hood. Every car has a “Vehicle Emission Control Information” placard under the hood. These stickers contain a lot of numbers, but look for the “U.S. EPA:” information. A Tier 3 car starts with “T3Bxx” The T3 means it’s a Tier 3 car.


Learn more

Here’s the official U.S. government source for fuel economy information, including Tier 3 vehicles, vehicle smog and greenhouse gas ratings at

This article was originally published on January 29, 2020.