Convince me why I shouldn't use regular gas.
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Joined: Apr 2022
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From: Tewksbury, MA
2008 S550
Convince me why I shouldn't use regular gas.
I bought my 08 S550 in April 2022 and bought premium gas. When it spiked to $4.50/ gallon I tried regular which was $1 per gallon less, saving $25 per fillup. I never noticed any decline in engine performance or gas mileage. Nor did I ever hear anything close to a knocking sound coming from the engine. I can get 25 mpg on highway driving around 70-75 mph. These cars have computers that adjust the air fuel mixture based on multiple variables.
I know people go on and on about how using regular on a car that should get premium can "damage" certain components. If this is true, tell me exactly what can be damaged. I've been using regular gas for about two years now and the car runs fantastic.
I know people go on and on about how using regular on a car that should get premium can "damage" certain components. If this is true, tell me exactly what can be damaged. I've been using regular gas for about two years now and the car runs fantastic.
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S500
the 273 is designed to run normal octane - it will go slower and do worse mpg if you put high octane fuels in it - however you must remember to buy premium brands (so additives like stabilisers, detergents, anti fungal stuff are made by adults not the local kebab shop) and ensure its not full of the death additive ethanol
ethanol trash fuel is worse for the planet (that's the whole idea....) it uses from start to burnt, more energy than it produces making the wheels go round - but it does make them more money and it does damage your vehicle
you'll use more and go slower at higher cost - whilst damaging your car and the planet
ethanol trash fuel is worse for the planet (that's the whole idea....) it uses from start to burnt, more energy than it produces making the wheels go round - but it does make them more money and it does damage your vehicle
you'll use more and go slower at higher cost - whilst damaging your car and the planet
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S500
the 221 has knock sensors that retards (delays) the ignition to reduce power and lower combustion chamber temps allowing the fuel to get over itself - its a virtuous circle if it doesn't clam down, power drops out till it does - its happening all the time making changes in milliseconds - however its not a miracle worker - terrible fuel, terrible driving, severe overheating, the wrong oils etc. will eventually lead to some engine damage
the 278 engine with CGI was built with this disease intentionally - and they now pretend to help the mismanagement with a later spec engine oil that doesn't contribute to the engine wear quite so much - designed to fail - in action - if you won't lease the flipping car we will take so much money out of your pocket you will have to walk or get on message !!!
by 2015 the idea has been lease for 4 years and then just scrap it !
.
Last edited by BOTUS; Oct 20, 2024 at 11:46 AM.
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From: Southern US
2010 E550, 273 Engine: 2012 S550, 278 Engine
the 273 is designed to run normal octane - it will go slower and do worse mpg if you put high octane fuels in it - however you must remember to buy premium brands (so additives like stabilisers, detergents, anti fungal stuff are made by adults not the local kebab shop) and ensure its not full of the death additive ethanol
ethanol trash fuel is worse for the planet (that's the whole idea....) it uses from start to burnt, more energy than it produces making the wheels go round - but it does make them more money and it does damage your vehicle
you'll use more and go slower at higher cost - whilst damaging your car and the planet
ethanol trash fuel is worse for the planet (that's the whole idea....) it uses from start to burnt, more energy than it produces making the wheels go round - but it does make them more money and it does damage your vehicle
you'll use more and go slower at higher cost - whilst damaging your car and the planet
The M273 in my E550 asks for min 91 Oct.
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From: DFW
SL63
What BOTUS defined detonation as, is absolutely true. However, he didn’t explain normal gasoline combustion. Gasoline is designed to combust in a ICE, very controlled, over a much longer time(comparative to detonation combustion, ie diesel). It is supposed to be smooth, with power being delivered with a steady increase throughout the combustion stroke, and a steady burn down at the end of the stroke . Higher octane fuels decrease any tendency for the combustion stroke to detonate, ie explode all at once. Detonation is zero to full expansion over a very short time, with no burn down at the end, and no build up at the start. That’s why detonation is so destructive to gasoline engines, they are not designed for it, they are not strengthened for it, they are not built for it, thus they will be destroyed by it, much earlier than their natural wear and tear would last.
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S500
>1500m 93 RON
sea level 95 std RON
higher performance engines 98 RON high octane
RON = research octane number, a rather basic useless test for anti-knock, but for some madness we stick with it
I forget what USA and Canada use - is it Mon motor octane number - an average of a usable car engine test and another - - these days seem to have changes its name (same units new name to AKI anti-knock index)
often you just take 4 units off RON to get equiv USA AKI ratings
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'91 964 Turbo, '02 E55's & '14 E63s-w
I use premium for one, it smells good, two, it's factory recommended and third, I hope high Tier gas is what they say it's suppose it to be.
There are two discussions I stay away from, premium vs regular and Mobil 1 vs other oils LOL
There are two discussions I stay away from, premium vs regular and Mobil 1 vs other oils LOL
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S500
usually - open the filler flap and read the info - as that's what you are expected to use (for the region the car was sold into)
a few vehicles used to be able to make use of high octane and they have two engine maps and it switches between the two based on what the knock sensors are saying
I have 2 BM bike that take this approach and the label says use 98 or higher octane (94 AKI) - or expect reduced performance and increased fuel consumption - but since the introduction of ethanol death fuel which "by chance" is a budget way to get some knock protection at very low cost, they have mostly given up on vehicles that run a better map.... maybe that's a break point where decent additives are required and as its all about theft and short vehicle life, today they prefer the accountants version
a few vehicles used to be able to make use of high octane and they have two engine maps and it switches between the two based on what the knock sensors are saying
I have 2 BM bike that take this approach and the label says use 98 or higher octane (94 AKI) - or expect reduced performance and increased fuel consumption - but since the introduction of ethanol death fuel which "by chance" is a budget way to get some knock protection at very low cost, they have mostly given up on vehicles that run a better map.... maybe that's a break point where decent additives are required and as its all about theft and short vehicle life, today they prefer the accountants version
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2014 S63 2010 ML350 Bluetec 2009 SL550
I'll never understand folks who somehow find the money for a premium auto but can't also find the money for proper maintenance and fuel. If you can't afford to feed it properly, buy something closer to your means.
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S500
this comes across as if you have no idea what you are talking about
running an octane rating above recommended - will make the car slower and waste more fuel - octane slows the burn, what you want is the optimal octane rating for the tune of the vehicle - on the 273 NA V8 its 91 AKI or 95 RON ROW
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2014 S63 2010 ML350 Bluetec 2009 SL550
Umm...I'm pretty sure I know *exactly* what I am talking about. The M273 is tuned for Premium fuel. I own one.
Not my first forum rodeo mate. I've seen permutations of this question on every forum I've ever read going back 30 years to the days of usenet.
Can you run a car designed for premium on regular ?: Sure...but for how long is the question here. "WHY" would you is a better question though. Don't buy the car if you cannot afford to own it....
Not my first forum rodeo mate. I've seen permutations of this question on every forum I've ever read going back 30 years to the days of usenet.
Can you run a car designed for premium on regular ?: Sure...but for how long is the question here. "WHY" would you is a better question though. Don't buy the car if you cannot afford to own it....
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From: Iowa
2008 CL550, 2022 EQB 300, 2023 EQS 450 4Matic
On a side note, are the fuel injectors in a M273 something that wear out/get too dirty and should be ideally replaced? My car has only 67,000 miles on it, but am thinking about winter projects to do and might add these to my list if so. I have done a lot of component replacements on my car, as I plan to keep it indefinitely.
Thread Starter
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Joined: Apr 2022
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From: Tewksbury, MA
2008 S550
My point is that if there is no downside to using regular gas, why drop an extra $25 a week? That's $1,000 a year. I do PM above and beyond what is required and drop in some Techron fuel injector cleaner from time to time.
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From: Occupied Palestine
2025 Maserati Grecale Folgore and 2024 Jaguar F-PACE SVR
That injector cleaner stuff always gets on my hands and the stink doesn't seem to wash off... probably gives you cancer too. So I'm OK with paying 50 cents extra per gallon instead of adding a $10 bottle of injector cleaner to 20 gallons myself. Call me crazy for wasting my money like that! 
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S500
Triple Down and RichDMB check the manual and use what it says
the word premium can relate to the quality not just the octane rating
The standard rating for petrol around the world is 95 octane RON (with USA and Canada at sea level using 91 AKI, which is the Average of RON and MON testing stds). Every car sold in Europe has its electronics tuned so that it can run properly on this fuel. In some foreign countries, you can get lower octane rated fuels, but if you add these to your car, it may cause 'knocking', the worst-case scenario there is the potential for engine failure if you use low octane fuel regularly.
At the other end of the spectrum, some high-performance cars may suffer from knock when using regular 95 octane fuel. If your car needs high octane fuel, it will be noted in the owner's manual, while most cars have a label on the inside of the fuel filler flap which shows what kind of fuel you can use
the word premium can relate to the quality not just the octane rating
The standard rating for petrol around the world is 95 octane RON (with USA and Canada at sea level using 91 AKI, which is the Average of RON and MON testing stds). Every car sold in Europe has its electronics tuned so that it can run properly on this fuel. In some foreign countries, you can get lower octane rated fuels, but if you add these to your car, it may cause 'knocking', the worst-case scenario there is the potential for engine failure if you use low octane fuel regularly.
At the other end of the spectrum, some high-performance cars may suffer from knock when using regular 95 octane fuel. If your car needs high octane fuel, it will be noted in the owner's manual, while most cars have a label on the inside of the fuel filler flap which shows what kind of fuel you can use
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04 E55 AMG (totaled), 07 S550 4Matic, 14 E63S
Here is the label inside the filler cap door on my 07 S550. I believe this translates to 91 US octane preferred but minimum 87, which is pretty typical of a luxury brand engine and has been for a long time.
US uses (RON+MON)/2 method for pump octane label (otherwise known as an average value). It says so right on the pumps.
Last edited by kevm14; Oct 21, 2024 at 01:38 PM.
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S500
so you get a Europe fuel grade sticker on a USA car - that's super helpful
two USA owners manuals put the correct data in there
2006 owners manual - page 490
Only use premium unleaded gasoline with a
minimum Posted Octane Rating of 91 (average of
96 RON/86 MON).
2010 owners manual - Page 403
Only use premium unleaded gasoline with
a minimum Posted Octane Rating of 91
(average of 96 RON/86 MON).
two USA owners manuals put the correct data in there
2006 owners manual - page 490
Only use premium unleaded gasoline with a
minimum Posted Octane Rating of 91 (average of
96 RON/86 MON).
2010 owners manual - Page 403
Only use premium unleaded gasoline with
a minimum Posted Octane Rating of 91
(average of 96 RON/86 MON).
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S500
yes they did in post #3
knock - pre-ignition - pinking, is all pretty much the same thing - its an explosive ignition of the fuel earlier than is desirable - effectively the fuel having a moment and is trying to reverse the engine rotation, just as the driver wants more forward motion - in a conventional piston engine we want petrol that burns with a very rapid expansion of a controlled flamefront, building pressure progressively - not a massive shockwave explosively damaging the piston crown, shattering the piston rings or eroding components in the combustion gas environment, and or causing localised overheating melting areas of the piston and smearing down the rings till its game over in a slower death
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S500
if you use super unleaded 94AKI in a std tune 273 USA region engine at altitudes around 0 to 1000m it will go slower, waste more fuel, and cost lots more money
it is ONLY designed to operate on 95 RON aka 91 AKI, read the owners manual PREMIUM UNLEADED relates to the quality not the octane rating
anyone suggesting otherwise is wrong and or stupid
it is ONLY designed to operate on 95 RON aka 91 AKI, read the owners manual PREMIUM UNLEADED relates to the quality not the octane rating
anyone suggesting otherwise is wrong and or stupid
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From: Southern US
2010 E550, 273 Engine: 2012 S550, 278 Engine
I bought my 08 S550 in April 2022 and bought premium gas. When it spiked to $4.50/ gallon I tried regular which was $1 per gallon less, saving $25 per fillup. I never noticed any decline in engine performance or gas mileage. Nor did I ever hear anything close to a knocking sound coming from the engine. I can get 25 mpg on highway driving around 70-75 mph. These cars have computers that adjust the air fuel mixture based on multiple variables.
I know people go on and on about how using regular on a car that should get premium can "damage" certain components. If this is true, tell me exactly what can be damaged. I've been using regular gas for about two years now and the car runs fantastic.
I know people go on and on about how using regular on a car that should get premium can "damage" certain components. If this is true, tell me exactly what can be damaged. I've been using regular gas for about two years now and the car runs fantastic.
However, I trialed with 89 oct fuel in my 2012 S550 and I get BETTER fuel mileage in highway driving (85% of my drives) than with 91-93 oct fuel. The difference is my S has the M278 Direct Injection engine. DI engine injects the fuel in the cylinder at the time fuel is needed for ignition and so does not allow the lower octane fuel to ignite prematurely “at will” and so prevents knocking with lower octane fuel.
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From: Portland, Oregon
2009 S600 V-12
One of the latest evolution is the Ford Explorer ST, twin turbo, direct injection into the cylinder, like a diesel engine. In the book it says, ahh, any octane of fuel can be used and will not damage the engine. It adjusts the timing and such to get no ping under boosted full acceleration. It does state in the manual however, to realize full torque and horsepower, use high octane fuel.
So, the designers say, yes, it’s going to function fine on lawnmower gas, for engines fuel injected through the intake manifold, forced induction. Fact is most likely the engine will be trashed if it’s boosted often on low octane lawnmower gas.
I read the pinging noise is the valves contacting the top of the pistons. Not great Mon. Not great.
Johnny
Last edited by johnnyrocket52; Oct 26, 2024 at 06:03 PM.
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S500
its a bit more complicated - boost effectively raised the compression ratio of an engine - pumping the air to make boost heats the air - lots of power raises engine temperatures - accountants want more money - the green lobby get confused - farmers love their subsidies getting rich doing nothing - governments have secret agendas and are run by morons
in the end a 273 uses 91 octane and a 278 dies from knock as direct injection creates odd fun and games and even merc changed the oil spec to try and help cover up the destroyed combustion chambers and oil consumption
ethanol makes farmers, the green lobby and the petrochemical criminals happy so everything is now ROW 95 ron - or USA 91 AKI and cars are more boring and designed to die in 4 years so its all irrelevant form now on.....
in the end a 273 uses 91 octane and a 278 dies from knock as direct injection creates odd fun and games and even merc changed the oil spec to try and help cover up the destroyed combustion chambers and oil consumption
ethanol makes farmers, the green lobby and the petrochemical criminals happy so everything is now ROW 95 ron - or USA 91 AKI and cars are more boring and designed to die in 4 years so its all irrelevant form now on.....
