Is Top Tier gasoline really necessary?

Dear Dave,
Do I really need to use Top Tier Premium Gasoline in my car? —Diane, 2024 Audi Q5

Dear Diane,
This actually has been a situation that occurred twice now with my wife’s car. It displayed an error code that indicated “Drive System: Malfunction! Please contact Service.” Unfortunately, the nearest Audi Service Department is 120 miles away and, yes, we knew that when we bought the car. We were also reassured by the salesman that, “It’s an Audi. It doesn’t need service!” I think he might have sold RVs at one time?

So, last year when the warning first came on we risked the 120-mile drive to take it to the Audi dealer. They hooked up the “special” On Board Diagnostic (OBD) reader and the code indicated fuel system contamination. The owner’s manual states that only Top Tier, Premium Gasoline should be used in the vehicle for the higher levels of detergents that keep the engine cleaner and creates less carbon deposits.

A recent AAA article posted that non-top tier gasoline left 19 times more engine deposits—which I find hard to believe. However, after spending an entire day just to have the error code reset and a quarter of the tank drained, we decided not to risk using “dirty gas”.

According to www.toptiergas.com:

TOP TIER™ Approved Fuels clean harmful carbon deposits left over in your engine from low-quality gas, restoring performance, fuel economy and drivability—all at no extra cost, in every octane, at stations you already trust.

I disagree with the statement “all at no extra cost”. The only station that sells Top Tier Premium in our area is Kwik Star. It is now $6+ per gallon, while regular 10% ethanol is $3.30 per gallon.

What makes TOP TIER™+ Approved Gasoline different?

Here is the description from toptiergas.com:

The new TOP TIER™+ fuel standards are designed for today’s state-of-the-art spark ignited engine technologies, especially high-efficiency GDI (Gasoline Direct Injection) fuel systems coupled with down-sized boosted engines. Modern GDI engines deliver maximum performance when operating cleanly. The new TOP TIER™+ Approved Gasoline standards add three new engine tests to help ensure cleaner fuel injectors, optimal emissions and more efficient combustion.

It goes on to state that 73% of new cars and trucks have the GDI fuel systems. It states that automobile manufacturers such as BMW, General Motors, Stellantis, Ford, Honda, Daimler Truck, Toyota, Volkswagen, Mercedes-Benz, International and Audi all recommend and sponsor the Top Tier program.

Also, TOP TIER™ prohibits the use of organometallic additives (what?) that are known to damage emissions after-treatment systems. Some of the emissions issues it lists are hard starting and stalling, which I think is ironic. This Audi has the feature that shuts the engine down when you come to a stop—which I hate—and then magically starts up a few times during a red light.

Another error message

Fast forward 8 months later and, once again, we have an error message. However, our local O’Reilly Auto Parts store has an OBD II that will read an Audi error message. Once again, it shows we have “bad gas”. I’ve had “bad gas” and wish we could just throw in a Beano and be done with it.

I assure you that we, meaning my wife, as I don’t get to drive the Audi, only purchases the Top Tier Premium non-ethanol at the only station in a 50-mile radius that has it. So why the error code?

We finally got a call back from the service technician at the Audi dealership and they suggested we tell Kwik Star that they have bad gas! Nope. He also suggested checking the fuel cap, as a loose cap could affect the pressure and give a false signal. WHAT? A thousand sensors, regulators, computers, and whatyamacallits, and a loose cap can put your car into limp mode?! Not buying it.

Not an uncommon situation

Then we got a call from another technician at the selling dealership as I had left a very direct message concerning the legitimacy of the bad gas/loose cap situation. I found that this is not an uncommon situation and there is a possible firmware update that is being considered. He suggested running the tank down to below 1/8th level, filling with known Top Tier fuel, and unhooking the negative cable on the battery for one minute to reset the code. I think he might have previously worked for Microsoft and pulled the “Have you tried restarting your computer?” diagnosis.

My 2016 Chevy Silverado has no problem with any type of fuel, although using E85 seems to be like flushing a toilet when it comes to fuel economy. I have also been told that running even 10% ethanol in small engines such as lawn mowers, weed eaters, and even generators is not good as it burns hotter.

However, I know hundreds of RV owners that have been running 10% or more in their rigs for years and running the generators with no heat issues. The only issue I know of is that not “exercising” the generator once a month to clean out the varnish will cause it to not start. However, I think that is with any type of gasoline.

Good ol’ days

I worked at a full-service gas station in high school and college and even owned my own for a few years with a friend and we actually pumped the gas, washed the windows, checked the oil and tires, and made change by counting back the money! We didn’t have those fancy registers that told you what change to give, remember getting a $20 for $10.50 in gas and counting back “50 cents is $11, one two three four dollars makes $15, and a five makes $20!” Of course, with Top Tier gas that would be less than two gallons today. OUCH.

I also have been secretly testing gasoline for years, leaving it in my lawn mower year-round without any stabilizer. Yes, it fires off every spring. And I have had the same oil in it for three years and, yes, there is a little “blue smoke” at the startup—but we have no mosquitoes.

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DAVE HAS ANSWERED MORE THAN 1,000 readers’ maintenance and repair questions. Read a directory here. There is so much to learn!

Dave Solberg is a leading expert in the RV industry and the author of the “RV Handbook.”

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