ORLANDO, Fla. – What to Know:
• TOP TIER gas does not mean premium gas.
• Automakers created the standard decades ago.
• TOP TIER doesn’t necessarily mean higher-priced gasoline.
For most Americans, when it comes to buying gas, one thing stands above the rest: price.
Convenience is nice (not driving too far just to save a penny or two), but when it comes right down to it, a couple of cents will usually determine whether you pull into the gas station immediately on the right or drive 20 feet to the next one across the intersection with a lower price.
That’s good for your wallet, but is it good for your car?
Before we go any further, this isn’t a story about whether or not premium gasoline is better for your vehicle than regular gasoline. The answer to that debate is simple: if your manufacturer recommends using regular gas, filling up with premium instead is literally flushing money down the drain. Why? Regular versus premium is about octane, and this story isn’t about octane – it’s about detergent.
Detergent?
Yup, detergent. It’s certainly not the same stuff you use in your washing machine, but the basic idea is similar: gasoline detergent helps keep things clean. For the rest of this story, remember this: clean engines are happy engines for a variety of reasons.
Why Is There Detergent in Our Gasoline in the First Place?
Here’s the backstory: as a requirement of the Clean Air Act Amendments of 1990, Congress directed the Environmental Protection Agency to ensure that gasoline sold to consumers contained additives designed to help engines and fuel systems stay clean.
How? By reducing engine deposits.
When gasoline burns in an engine, it doesn’t leave everything perfectly clean. Over time, carbon and other deposits can accumulate on critical engine and fuel-system components like fuel injectors and intake valves – parts designed to precisely control the fuel and air your engine needs.
Think of it like a dirty showerhead in your bathroom: tiny openings are designed to spray water in a very specific pattern, but when deposits start building up, they can partially clog those openings and change the spray. A fuel injector works on a much smaller and more precise scale, but the problem is the same: instead of restricting the spray of water, deposits can restrict the flow of fuel and interfere with the way the injector sprays it.
Detergent additives help control those deposits, keeping critical components cleaner and helping your engine continue operating the way it was designed to.
The mandate for detergent in gasoline went into effect on January 1, 1995, and although it was a step in the right direction, it wasn’t good enough for everyone. At this point, you might be thinking the idea of “TOP TIER” gasoline – a higher standard than what was being mandated by the feds – was something cooked up by oil companies to convince you to spend more at the pump.
Nope.
The standard came from the companies that make your car.
General Motors Was the Driving Force
In 2004, General Motors, with the support of BMW, Toyota, and Honda, developed the TOP TIER gasoline standard because the automakers wanted gasoline with better deposit-control performance than what was required under the federal minimum. Their solution wasn’t simply to require more detergent – instead, they established tougher performance tests that gasoline had to pass to earn the TOP TIER designation.
ChevronTexaco was the first U.S. gasoline marketer to meet the new TOP TIER standards, announcing in June 2004 that its gasoline had been approved under the program.
Today, more than 50 companies, cooperatives, and tribal operators sell TOP TIER-approved gasoline in the U.S. through dozens of different brands. The program has previously estimated that TOP TIER gasoline is available at roughly 75,000 gas stations nationwide and, in 2024, reported more than 100,000 licensed stations worldwide.
What brands are considered TOP TIER? You’ll recognize many of them – and you might also recognize the names they use to market their fuels and detergent technology: BP/Amoco have Invigorate, Chevron has Techron, Exxon/Mobil market Synergy, and Shell has V-Power NiTRO+.
Costco, through its Kirkland Signature gasoline, is currently the only one of the three major warehouse clubs (Costco, Sam’s Club, and BJ’s) listed as TOP TIER-approved. Other major brands selling TOP TIER gasoline include CITGO, Marathon, Phillips 66/Conoco, QuikTrip, Sunoco, and Valero.
Does It Really Make a Difference?
So, automakers say TOP TIER gasoline is better at keeping your engine clean, but does it actually make a difference?
Well, AAA wanted to know the same thing.
In 2016, the auto club commissioned an independent laboratory to compare TOP TIER gasoline with fuel that met federal detergent requirements but did not meet the TOP TIER standard. The test focused on something we’ve already talked about: engine deposits.
Researchers subjected six gasoline samples – three TOP TIER and three non-TOP TIER – to an industry-standard engine test representing about 4,000 miles of driving. Afterward, they took the engines apart and measured the deposits left behind.
The difference was significant.
The AAA-commissioned study found the non-TOP TIER gasoline produced 19 times more intake-valve deposits than the TOP TIER gasoline tested. The specifics: the non-TOP TIER fuels averaged about 660 milligrams of deposits per valve, compared with just 34 milligrams for the TOP TIER fuels. For a second, don’t think about milligrams – think back to that showerhead. Both fuels left some buildup, but the non-TOP TIER gasoline left about 19 times more.
There is one important caveat to the study: it was conducted in 2016, so it isn’t a comparison of every gasoline being sold today. However, the AAA test remains an important independent laboratory comparison of TOP TIER and non-TOP TIER fuels.
Does TOP TIER Mean More Expensive Gas?
There’s a perception that buying TOP TIER means filling up at one of the big-name gas stations – and paying big-name prices. But that’s not necessarily the case. Chevron, Shell, Exxon, Mobil, and BP all sell TOP TIER gasoline, but so do brands like CITGO, QuikTrip, Costco, and Sunoco.
Meanwhile, some other familiar names – including Speedway, RaceTrac, Circle K, and 7-Eleven – are not currently listed as TOP TIER-approved gasoline brands. That doesn’t mean the gasoline they sell is bad. It still has to meet federal requirements, including the EPA’s minimum detergent standards. It simply means their gasoline has not been certified as meeting the additional TOP TIER performance standard.
So instead of assuming the most expensive station has the “best” gasoline – or that the cheapest has the worst – check whether the fuel is TOP TIER-approved.
But Wait, There’s More: TOP TIER Gets an Upgrade
In 2024, the TOP TIER Fuels program announced an updated performance standard called TOP TIER+, designed to extend the TOP TIER standard to newer engines. In particular, the update targeted gasoline direct injection, or GDI – technology now found in many newer vehicles.
TED Talk time: in a traditional port fuel-injection engine, gasoline is sprayed into the intake port before entering the combustion chamber. In a GDI engine, the injector sprays gasoline directly into the combustion chamber, and under much higher pressure. GDI technology improves the precision of fuel delivery, but it also creates different challenges when it comes to deposits – particularly on the tip of the fuel injector itself. TOP TIER+ adds new engine testing, including a test specifically designed to measure GDI fuel-injector cleanliness.
Bottom line: as engines have changed, the TOP TIER standard has changed with them.
You may already be buying TOP TIER+ without knowing it: BP and Amoco announced in 2026 that their gasoline with Invigorate had earned the TOP TIER+ designation, joining Costco’s Kirkland Signature gasoline among the national brands meeting the newer standard.
So, does all of this mean you should drive across town or pay significantly more just to fill up with TOP TIER gasoline? Probably not. But the next time you’re comparing prices at two stations, don’t assume the higher price or bigger brand name tells you which gasoline meets the higher detergent standard. Look for the TOP TIER logo – or check the approved-brand list – and then compare the price.
And remember: the most important thing is still to use the octane recommended by your vehicle’s manufacturer. TOP TIER isn’t about buying more expensive gas – it’s about being a little more selective about the gasoline you buy.
One last thing: if you want to know whether a station near you sells TOP TIER gasoline, the program offers a TOP TIER Station Finder app for Apple and Android devices, along with an online station finder. The program says it is also updating those tools to identify stations selling TOP TIER+.