Do you use premium gas in your glc?
Senior Member
Joined: Feb 2015
Posts: 393
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From: S. Ca.
2015 C300, 2015 F-350 Platinum, 1969 Mach 1 428cj, 2007 Roadking
You are correct. Fuel sellers "imply" that higher octane is better, but in reality only in terms of antiknock properties. The fuel additive packages are otherwise the same for the different rated fuels. Most folks don't know that the mid grade fuel is actually a blend of regular and premium done at the pump. There is no 3rd storage tank. You are blowing money using a higher octane than needed. You can use lower octane fuel and the antiknock sensors in the engine will retard timing so that no damage is done. You will get lower performance and mileage as a result.
Junior Member
Joined: Feb 2017
Posts: 20
Likes: 2
Mercedes GLC250
As I understand, premium fuel may have 2 advantages.
The first is more performance. In the Netherlands and Germany, premium fuel have additives to keep the motor more clean, and do not increase the RON of the petrol. An investigation of ADAC shows that the effect is negligible: https://www.adac.de/infotestrat/tank...cePageId=49341 (in German)
The second is to keep your motor clean. A Dutch consumer program did some investigation, and motor revision experts say the can't detect any difference of any significance with the cars that they maintain:
(in Dutch)
In the second episode, a petrol station employee says that the basic component of the premium fuel is exactly the same petrol, and after delivering an additive substance (1 liter on 10.000 liter) is added. That's about 20-25cl on an average tank of 50 to 65 liter (it can be very concentrated of course). https://www.youtube.com/watch?v=fgC8...=536.863439778
All 'n' all it looks more like a marketing gimmick to sell the same product for more money, and in controlled laboratory conditions measurable effects might be seen. A nice observation in the above documentary is that the premium fuel is said to deliver more performance as well as cleaner engines, but THE way to pollute your engine more is to push more power out of it. If you want to keep your engine clean, your driving habits are more important.
If premium means a higher octane level (e.g. from 95 to 98), the performance increase can be measured, just like 95 to 91 gives less performance.
The are countries where very low quality fuel is being sold, and in such a case it is important to buy "premium" fuel (i.e. at respected companies with a trustable source of petrol).
The first is more performance. In the Netherlands and Germany, premium fuel have additives to keep the motor more clean, and do not increase the RON of the petrol. An investigation of ADAC shows that the effect is negligible: https://www.adac.de/infotestrat/tank...cePageId=49341 (in German)
The second is to keep your motor clean. A Dutch consumer program did some investigation, and motor revision experts say the can't detect any difference of any significance with the cars that they maintain:
In the second episode, a petrol station employee says that the basic component of the premium fuel is exactly the same petrol, and after delivering an additive substance (1 liter on 10.000 liter) is added. That's about 20-25cl on an average tank of 50 to 65 liter (it can be very concentrated of course). https://www.youtube.com/watch?v=fgC8...=536.863439778
All 'n' all it looks more like a marketing gimmick to sell the same product for more money, and in controlled laboratory conditions measurable effects might be seen. A nice observation in the above documentary is that the premium fuel is said to deliver more performance as well as cleaner engines, but THE way to pollute your engine more is to push more power out of it. If you want to keep your engine clean, your driving habits are more important.
If premium means a higher octane level (e.g. from 95 to 98), the performance increase can be measured, just like 95 to 91 gives less performance.
The are countries where very low quality fuel is being sold, and in such a case it is important to buy "premium" fuel (i.e. at respected companies with a trustable source of petrol).
Newbie
Joined: Jun 2017
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From: SoCal
GLC 300
Senior Member
Joined: Apr 2016
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From: Australia
GLC 250D
I haven't watched that video, as I gather that it's in Dutch, but what you say mostly contradicts what I found when I researched the issue. If you use lower octane fuel than recommended, then you would get worse performance and economy, as the vehicle knock-detection systems would retard the timing to prevent detonation. But everything I read suggested that there were no performance, economy or engine cleanliness benefits to using higher than recommended octane. If someone has hard evidence (not just a a talking head) that there are, I'd be keen to read it. I do agree that the claim that using higher octane fuel than recommended appears to be just marketing.
Junior Member
Joined: Feb 2017
Posts: 20
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Mercedes GLC250
I found another (Dutch) movie, where it is obvious that the big petrol companies (Shell, BP, Total) get their fuel from exactly the same point, i.e. the basic petrol is not different:
The journalists were fined by the police because they were filming the topic.
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Joined: Feb 2007
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From: Houston - Clear Lake
C63 coupe, Z3M Roadster garage queen
It's really interesting to see how the definition of "premium" varies across the globe.
In the US, the difference between regular, mid and premium is only in the octane level. Mercedes specifies 91 octane in the US, and in the US that's premium. If you run lower octane, you will likely give up a little performance and you MAY have problems with knock if the engine management system can't adjust for it. Knock can cause long-term damage.
In the US, EPA requires that all gasoline must contain a specified minimum level of additives (mostly detergents). In the US, there is no difference in the required additives between regular and premium. This minimum level isn't enough to keep most engines gunk-free. The major auto manufacturers (including Mercedes) established a higher standard, called "Top Tier" gasoline, to help protect the performance and emissions of their engines. Look for the "Top Tier" label on pumps to see if you are getting the additional detergent additives. Check the list of licensed retailers at www.toptiergas.com/licensedbrands
In the US, the difference between regular, mid and premium is only in the octane level. Mercedes specifies 91 octane in the US, and in the US that's premium. If you run lower octane, you will likely give up a little performance and you MAY have problems with knock if the engine management system can't adjust for it. Knock can cause long-term damage.
In the US, EPA requires that all gasoline must contain a specified minimum level of additives (mostly detergents). In the US, there is no difference in the required additives between regular and premium. This minimum level isn't enough to keep most engines gunk-free. The major auto manufacturers (including Mercedes) established a higher standard, called "Top Tier" gasoline, to help protect the performance and emissions of their engines. Look for the "Top Tier" label on pumps to see if you are getting the additional detergent additives. Check the list of licensed retailers at www.toptiergas.com/licensedbrands
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From: Houston - Clear Lake
C63 coupe, Z3M Roadster garage queen
This is true in the US and Canada too. All the refineries make each grade of gasoline to meet a specific standard. It all gets fed to common pipelines and pumped into common tanks at distribution centers across the country. Fuel delivery trucks from all the retailers fill up from the same tanks. What's different is the content and concentration of the additive package that gets fed into the trucks as they load. Each of the major retailers has a different additive treatment.
Member
Joined: Feb 2023
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From: Suburban Chicago in Illinois
2024 GLC-300 & 2022 GLE-350
I only put PREMIUM "Top Tier" certified gasoline in our 2023 GLE350 and 2024 GLC300. In the Chicago area, only MOBIL and SHELL are "Top Tier". The Top Tier label is affixed to the pump.
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From: DFW
SL63
Along come the new kid on the block, Top Tier+ fuel.
Emphasis on the plus!
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'21 AMG53 wDPP & ARC, 19 GLC300 - Former-03 C240,2 ML BlueTecs,20 GLE450 E-ABC,15 Cayenne D,17 Macan
Found a link - https://www.toptiergas.com/gasoline-brands/
Last edited by mikapen; Oct 2, 2025 at 02:27 AM.
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From: Colorado
G550
I recall the "Super Shell with Platformate" TV commercials that aired in the '60's. Shell gasoline was promoted as containing this miracle mileage enhancing fuel additive, and the commercial showed two vehicles -- one with Shell with Platformate and the other without Platformate -- driving across a desert, where the without Platformate vehicle coasts to a stop and the with Platformate vehicle drives on for several more miles. Shell had to pull the ads when it was revealed Platformate was nothing more than its proprietary name for tetra-ethyl lead, which was in every gasoline brand. Oil companies have always been scoundrels.
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From: Colorado
'21 AMG53 wDPP & ARC, 19 GLC300 - Former-03 C240,2 ML BlueTecs,20 GLE450 E-ABC,15 Cayenne D,17 Macan
I recall the "Super Shell with Platformate" TV commercials that aired in the '60's. Shell gasoline was promoted as containing this miracle mileage enhancing fuel additive, and the commercial showed two vehicles -- one with Shell with Platformate and the other without Platformate -- driving across a desert, where the without Platformate vehicle coasts to a stop and the with Platformate vehicle drives on for several more miles. Shell had to pull the ads when it was revealed Platformate was nothing more than its proprietary name for tetra-ethyl lead, which was in every gasoline brand. Oil companies have always been scoundrels.
Most manufacturers have a proprietary additive that they advertise.
Today, Shell is advertising "V-Power NiTRO+." Nothing wrong with that, in my mind.
The reason Shell removed those ads was that the cars that ran out of fuel were black and the ones that kept running were white. Dick Gregory, a Black comedian, made a big stink about the "racist" implications of the ads.
Every Brand has some sort of specialty that they advertise, even if may not be exclusive to them.
Esso had a Tiger in the Tank with a proprietary ingredient, but PETA didn't weigh in. They also let Kellogg's Tony the Tiger off the hook.
BTW my cars seem to run the best on Shell. It could be my imagination, it could be that I'm susceptible to advertising, or that the two MPG improvement that I actually see might be true.
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From: DFW
SL63
Turbocharged and supercharged engines need the proper octane rating more than normally aspirated.
In the case of expense analysis, the money saved on using a lower octane rating in the charged engines, is less than the repair or replacement cost of the engine, and likely shorter than projected engine endurance.
In the case of expense analysis, the money saved on using a lower octane rating in the charged engines, is less than the repair or replacement cost of the engine, and likely shorter than projected engine endurance.
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From: Colorado
'21 AMG53 wDPP & ARC, 19 GLC300 - Former-03 C240,2 ML BlueTecs,20 GLE450 E-ABC,15 Cayenne D,17 Macan
Lower octane in engines from the last 30 years or so will retard the timing. Newer ones will adjust the entire engine mapping to protect themselves.
In either case, your mileage and performance suffers.
You'll get the highest grade detergent packages with the highest grade available, and the "Top Tier Plus" mentioned above is aimed directly at gasoline direct injection (GDI) engines. Which is what we have.
In either case, your mileage and performance suffers.
You'll get the highest grade detergent packages with the highest grade available, and the "Top Tier Plus" mentioned above is aimed directly at gasoline direct injection (GDI) engines. Which is what we have.
Member
Joined: Feb 2023
Posts: 82
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From: Suburban Chicago in Illinois
2024 GLC-300 & 2022 GLE-350
-Allen
Update 10/2/2025 - Here we are: TOP TIER PLUS.
What it is
- Goes beyond EPA standards:
While EPA standards set a minimum level of detergent additives, the Top Tier™ program and its Plus version set stricter requirements developed by automakers.
- Focus on GDI engines:
GDI engines operate differently than older engine designs, requiring higher levels of detergency to prevent carbon buildup.
- An advanced fuel standard:
Top Tier Plus was developed to meet the increased performance and cleaning needs of modern gasoline direct injection (GDI) engines.
Last edited by AllenChicago; Oct 2, 2025 at 09:13 PM.
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G550
Actually, Platformate was different from tetra-ethyl lead, and actually enhanced fuel economy. It was an additional ingredient that was created over a Platinum catalyst.
Most manufacturers have a proprietary additive that they advertise.
Today, Shell is advertising "V-Power NiTRO+." Nothing wrong with that, in my mind.
The reason Shell removed those ads was that the cars that ran out of fuel were black and the ones that kept running were white. Dick Gregory, a Black comedian, made a big stink about the "racist" implications of the ads.
Every Brand has some sort of specialty that they advertise, even if may not be exclusive to them.
Esso had a Tiger in the Tank with a proprietary ingredient, but PETA didn't weigh in. They also let Kellogg's Tony the Tiger off the hook.
BTW my cars seem to run the best on Shell. It could be my imagination, it could be that I'm susceptible to advertising, or that the two MPG improvement that I actually see might be true.
Most manufacturers have a proprietary additive that they advertise.
Today, Shell is advertising "V-Power NiTRO+." Nothing wrong with that, in my mind.
The reason Shell removed those ads was that the cars that ran out of fuel were black and the ones that kept running were white. Dick Gregory, a Black comedian, made a big stink about the "racist" implications of the ads.
Every Brand has some sort of specialty that they advertise, even if may not be exclusive to them.
Esso had a Tiger in the Tank with a proprietary ingredient, but PETA didn't weigh in. They also let Kellogg's Tony the Tiger off the hook.
BTW my cars seem to run the best on Shell. It could be my imagination, it could be that I'm susceptible to advertising, or that the two MPG improvement that I actually see might be true.
Member
Joined: Feb 2023
Posts: 82
Likes: 25
From: Suburban Chicago in Illinois
2024 GLC-300 & 2022 GLE-350
Thanks for the WEALTH of useful information! I seem to get the most miles pumped into the thank at Shell stations in St. Louis and further south. The 2022 GLE350 gets at least 530 miles on a full tank with southern Shells. Here in the Chicago area, or Wisconsin, or Michigan, I'm lucky to get get 470 miles on a fill-up. Very strange!
