Top Tier Fuel...I was 100% wrong. It really does make a difference
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From: Pacific Northwest
2001 S600 V12 Sold, 2011 Jaguar XFR Sold, 2017 S550 4-Matic, 2018 S63 AMG Sedan
Top Tier Fuel...I was 100% wrong. It really does make a difference
I posted this in the W222 section about a month ago and I think there's some valuable information included for you guys too.
Not sure if you guys care much about this part of maintenance or not, but I'd like to eek out every mile of life from my current car. I've been using Safeway gas over the last few years. I switched from Costco gas because one of my previous cars sems to have run better on Safeway gas versus Costco gas. And since I've always bought premium, I thought I was gettting top tier gas. I was wrong, I'm switching on my fill up to Costco, Chevron, Shell or even...ARCO. I never thought I'd ever say Arco. The YT video is below and the fuel report is attached.
Prior to finding this article, I thought octane rating was the most important factor in which gasoline to choose and use. I had been told by a fuel delivery driver that all not premium gas was the same; literally pulled from the same tanks and nothing was different regardless of brand. He told me that the only difference was in premium gas, where each brand puts an additive in the gas that’s in the storage tanks at the distribution center, not in the truck or at the gas station. My choice in fuel to purchase was based on this, and it’s not accurate. It might have been accurate at that time, but is not the way gasoline is distributed now.
Top Tier fuel has nothing to do with Octane levels, the 2 are totally independent. Information from Report: “Some consumers may associate gasoline quality with fuel grade (premium vs. regular) or octane number, which is a mistaken assumption. Motorists should use the fuel grade recommended by the vehicle manufacturer in the owner’s manual.”
Summation regarding octane: Gasoline doesn’t “burn” in an engine, it actually “explodes”. Gasoline’s special quality that makes it the perfect fuel for ICE is how it explodes under heat and pressure. The spark from the plug ignites the mixture at the optimal time and piston position. Octane level, or octane rating, measures how resistant a fuel is to premature ignition, or "knocking", in an engine. Further explanation: “Octane ratings are measures of fuel stability. These ratings are based on the pressure at which a fuel will spontaneously combust (auto-ignite) in a testing engine. The octane number is actually the simple average of two different octane rating methods—motor octane rating (MOR) and research octane rating (RON)—that differ primarily in the specifics of the operating conditions. The higher an octane number, the more stable the fuel. Retail gasoline stations in the United States sell three main grades of gasoline based on the octane level:
The goal of the study was to see if the additives in Toptier gasoline actually helped reduce carbon buildup on intake valves. This study was NOT about fuel economy or performance. It can be argued that you could expect better performance due to a cleaner fuel system, but there was nothing in the test that talked about economy or performance increases or efficiency. If that was the case, then why do the study?? In a lot of today’s engines, the fuel injectors spray fuel directly into the combustion chamber instead of into the intake port. GDI engines spray atomized fuel into the combustion chamber. Port injection (PI) engines spray fuel into the intake ports. Since PI engines spray fuel into the intakes, the fuel cleans off carbon deposits from the back and head of the intake valves. On GDI engines this does not happen. Therefore, GDI engines can suffer from carbon buildup on the back of the intake valves, reducing efficiency and causing even more carbon buildup over time. Over time carbon buildup can cause:
· Reduced engine power
· Poor fuel delivery
· Valves sticking
· Damaged valves or pistons
· Rough idle, misfires, and increased emissions
In the case of the M177/M178 engines the increased emissions will cause the oil separators to clog, which leads to increased crankcase pressure and eventually leaking valve covers, or the dreaded rear main seal failure…OUCH!!! That means a very expensive repair.
That’s why it’s important. Having said that; it’s only relevant to GDI engines. They tested different Toptier gasoline to see if they in fact helped to reduce carbon buildup and to also remove existing carbon buildup. All gasoline used in the test was Premium 93 Octane. Excerpt from report:
“Premium fuel (93 octane) was selected as the octane grade for this evaluation due to the trend of some brands to put a slightly higher concentration of detergent in their premium grades of fuel. Even non-TOP TIER gasolines may include additional additives in their premium grades, so this choice in octane was intended to eliminate that variable. Retailers that sell TOP TIER gasoline are required to meet TOP TIER standards in all grades of fuel, not just premium. For TOP TIER gasoline, the test results (fig. 8) should be consistent if the test was conducted with regular grade gasoline. Testing non-TOP TIER brands of regular grade gasoline would likely result in similar or higher levels of carbon deposits on critical engine components.”
You can read about the methodology and test parameters, but I wanted to tell you what I thought was important.
The additives in the gasoline are designed to:
Clean the injectors as they flow through the fuel system
Survive the combustion process and get into the crankcase oil through normal blowby. Then flow through the EGR system and clean the valves as they are returned into the combustion chamber.
The additives actually did that, and that’s amazing!!
In order to make it fair, they tested Toptier fuels and non Toptier fuels. Here’s an excerpt of the results:
4.3 Test Results
The weight of the intake valve deposits was measured with a high accuracy lab scale. The weight of the deposits on all four intake valves were averaged into the values shown below (fig. 8) to represent each brand of fuel. The non-TOP TIER gasolines resulted in a group average 660.6mg of deposits per intake valve. The TOP TIER gasolines had a group average of 34.1mg per valve or roughly nineteen times fewer deposits than the non-TOP TIER gasolines.
Lastly; who did the test and was it objective? This was an objective test performed by the American Automobile Association, AAA, or Triple-A. They tested to see if paying the additional cost at the gas pump was worth the extra money. In their opinion, it was. In their report, they stated that Toptier gas cost $.10 cents per gallon more than non Toptier. That’s not the case where I live, but they bought gasoline in Texas, and tests were performed back in 2016. Also, consumers have the choice of purchasing fuel system cleaners over the counter, and it has the same effect. The ingredient that does the most work is PEA, along with some other compounds.
Here's the video that talks about the difference between octane and additives, and carbon build-up.
Not sure if you guys care much about this part of maintenance or not, but I'd like to eek out every mile of life from my current car. I've been using Safeway gas over the last few years. I switched from Costco gas because one of my previous cars sems to have run better on Safeway gas versus Costco gas. And since I've always bought premium, I thought I was gettting top tier gas. I was wrong, I'm switching on my fill up to Costco, Chevron, Shell or even...ARCO. I never thought I'd ever say Arco. The YT video is below and the fuel report is attached.
Prior to finding this article, I thought octane rating was the most important factor in which gasoline to choose and use. I had been told by a fuel delivery driver that all not premium gas was the same; literally pulled from the same tanks and nothing was different regardless of brand. He told me that the only difference was in premium gas, where each brand puts an additive in the gas that’s in the storage tanks at the distribution center, not in the truck or at the gas station. My choice in fuel to purchase was based on this, and it’s not accurate. It might have been accurate at that time, but is not the way gasoline is distributed now.
Top Tier fuel has nothing to do with Octane levels, the 2 are totally independent. Information from Report: “Some consumers may associate gasoline quality with fuel grade (premium vs. regular) or octane number, which is a mistaken assumption. Motorists should use the fuel grade recommended by the vehicle manufacturer in the owner’s manual.”
Summation regarding octane: Gasoline doesn’t “burn” in an engine, it actually “explodes”. Gasoline’s special quality that makes it the perfect fuel for ICE is how it explodes under heat and pressure. The spark from the plug ignites the mixture at the optimal time and piston position. Octane level, or octane rating, measures how resistant a fuel is to premature ignition, or "knocking", in an engine. Further explanation: “Octane ratings are measures of fuel stability. These ratings are based on the pressure at which a fuel will spontaneously combust (auto-ignite) in a testing engine. The octane number is actually the simple average of two different octane rating methods—motor octane rating (MOR) and research octane rating (RON)—that differ primarily in the specifics of the operating conditions. The higher an octane number, the more stable the fuel. Retail gasoline stations in the United States sell three main grades of gasoline based on the octane level:
- Regular (the lowest octane fuel–generally 87)
- Midgrade (the middle range octane fuel–generally 89–90)
- Premium (the highest octane fuel–generally 91–94)
The goal of the study was to see if the additives in Toptier gasoline actually helped reduce carbon buildup on intake valves. This study was NOT about fuel economy or performance. It can be argued that you could expect better performance due to a cleaner fuel system, but there was nothing in the test that talked about economy or performance increases or efficiency. If that was the case, then why do the study?? In a lot of today’s engines, the fuel injectors spray fuel directly into the combustion chamber instead of into the intake port. GDI engines spray atomized fuel into the combustion chamber. Port injection (PI) engines spray fuel into the intake ports. Since PI engines spray fuel into the intakes, the fuel cleans off carbon deposits from the back and head of the intake valves. On GDI engines this does not happen. Therefore, GDI engines can suffer from carbon buildup on the back of the intake valves, reducing efficiency and causing even more carbon buildup over time. Over time carbon buildup can cause:
· Reduced engine power
· Poor fuel delivery
· Valves sticking
· Damaged valves or pistons
· Rough idle, misfires, and increased emissions
In the case of the M177/M178 engines the increased emissions will cause the oil separators to clog, which leads to increased crankcase pressure and eventually leaking valve covers, or the dreaded rear main seal failure…OUCH!!! That means a very expensive repair.
That’s why it’s important. Having said that; it’s only relevant to GDI engines. They tested different Toptier gasoline to see if they in fact helped to reduce carbon buildup and to also remove existing carbon buildup. All gasoline used in the test was Premium 93 Octane. Excerpt from report:
“Premium fuel (93 octane) was selected as the octane grade for this evaluation due to the trend of some brands to put a slightly higher concentration of detergent in their premium grades of fuel. Even non-TOP TIER gasolines may include additional additives in their premium grades, so this choice in octane was intended to eliminate that variable. Retailers that sell TOP TIER gasoline are required to meet TOP TIER standards in all grades of fuel, not just premium. For TOP TIER gasoline, the test results (fig. 8) should be consistent if the test was conducted with regular grade gasoline. Testing non-TOP TIER brands of regular grade gasoline would likely result in similar or higher levels of carbon deposits on critical engine components.”
You can read about the methodology and test parameters, but I wanted to tell you what I thought was important.
The additives in the gasoline are designed to:
Clean the injectors as they flow through the fuel system
Survive the combustion process and get into the crankcase oil through normal blowby. Then flow through the EGR system and clean the valves as they are returned into the combustion chamber.
The additives actually did that, and that’s amazing!!
In order to make it fair, they tested Toptier fuels and non Toptier fuels. Here’s an excerpt of the results:
4.3 Test Results
The weight of the intake valve deposits was measured with a high accuracy lab scale. The weight of the deposits on all four intake valves were averaged into the values shown below (fig. 8) to represent each brand of fuel. The non-TOP TIER gasolines resulted in a group average 660.6mg of deposits per intake valve. The TOP TIER gasolines had a group average of 34.1mg per valve or roughly nineteen times fewer deposits than the non-TOP TIER gasolines.
Lastly; who did the test and was it objective? This was an objective test performed by the American Automobile Association, AAA, or Triple-A. They tested to see if paying the additional cost at the gas pump was worth the extra money. In their opinion, it was. In their report, they stated that Toptier gas cost $.10 cents per gallon more than non Toptier. That’s not the case where I live, but they bought gasoline in Texas, and tests were performed back in 2016. Also, consumers have the choice of purchasing fuel system cleaners over the counter, and it has the same effect. The ingredient that does the most work is PEA, along with some other compounds.
Here's the video that talks about the difference between octane and additives, and carbon build-up.
Thread Starter
MBWorld Fanatic!
Joined: Aug 2007
Posts: 1,830
Likes: 793
From: Pacific Northwest
2001 S600 V12 Sold, 2011 Jaguar XFR Sold, 2017 S550 4-Matic, 2018 S63 AMG Sedan
I can help but wonder if some of the RMS failures could have been avoided by using the right type of gas and/or OTC additives???
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2018 AMG E63s Ed1
Senior Member
Joined: Jun 2023
Posts: 426
Likes: 291
2018 AMG E63s Ed1
the fuel is direclty injected into the cylinder unlike port injection which does hit the valves (and coincidentally assist in keeping the valves cleaner).
From a detonation perspective... again not relevant as if it is detonating, the fuel octane is to low and it will destroy the weaker part of the piston first (usually the rings but if the detonation is bad enough, it can melt the piston/head).
From a gas bypass perspective, if you are bypassing that much gas, there was detonation OR the ring were gapped incorrectly which lead to the excessive bypass causing higher than wanted or needed Crank case pressure.
From a detonation perspective... again not relevant as if it is detonating, the fuel octane is to low and it will destroy the weaker part of the piston first (usually the rings but if the detonation is bad enough, it can melt the piston/head).
From a gas bypass perspective, if you are bypassing that much gas, there was detonation OR the ring were gapped incorrectly which lead to the excessive bypass causing higher than wanted or needed Crank case pressure.
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From: USA
2018 E63S Wagon, 2017 Z51 Corvette
I'm a little confused by this - are we saying that the E63S is direct injection so no fuel passes through the intake valve. EGR does go through the intake valve and that is what creates carbon build up? If those statements are true what good is any fuel additive, at least as far as the intake valves are concerned?
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Thread Starter
MBWorld Fanatic!
Joined: Aug 2007
Posts: 1,830
Likes: 793
From: Pacific Northwest
2001 S600 V12 Sold, 2011 Jaguar XFR Sold, 2017 S550 4-Matic, 2018 S63 AMG Sedan
the fuel is direclty injected into the cylinder unlike port injection which does hit the valves (and coincidentally assist in keeping the valves cleaner).
From a detonation perspective... again not relevant as if it is detonating, the fuel octane is to low and it will destroy the weaker part of the piston first (usually the rings but if the detonation is bad enough, it can melt the piston/head).
From a gas bypass perspective, if you are bypassing that much gas, there was detonation OR the ring were gapped incorrectly which lead to the excessive bypass causing higher than wanted or needed Crank case pressure.
From a detonation perspective... again not relevant as if it is detonating, the fuel octane is to low and it will destroy the weaker part of the piston first (usually the rings but if the detonation is bad enough, it can melt the piston/head).
From a gas bypass perspective, if you are bypassing that much gas, there was detonation OR the ring were gapped incorrectly which lead to the excessive bypass causing higher than wanted or needed Crank case pressure.
I do wonder again about the fuels used by the guy who've suffered RMS failures.
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From: Seattle
'19 E63S, ‘16 CLS63 RIP, '09 E63 Gone, '06 M5 Gone, '97 Supra TT Gone
RMS still failed at 39k miles.
Thread Starter
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From: Pacific Northwest
2001 S600 V12 Sold, 2011 Jaguar XFR Sold, 2017 S550 4-Matic, 2018 S63 AMG Sedan
I think I would be a good test case for the answer to that question being a massive NO. RMS has to do with crankcase pressure, not with gas. I have never, ever filled my tank with anything but Shell or Chevron premium and regularly use top tier injector cleaning additives. I am maniacal about the quality of my gas.
RMS still failed at 39k miles.
RMS still failed at 39k miles.
Any chance you normally get your gas early or late in the day, or from a station that doesn't have a high turn rate on their fuel??
