Will 91 octane hurt my engine?
Super Member
Joined: May 2019
Posts: 671
Likes: 288
From: Omaha, NE
2007 S600
There’s theoretical perfection, and then there is practical application. The answer is, no, 91 octane gasoline will not hurt your engine, nor will 10% ethanol. Both have been the norm in much of the USA for decades now, and Mercedes-Benz is quite well aware of this. I ran my S600 on 91 non-ethanol when possible, but it routinely got 10% blend when on road trips and when filling it at Costco. Zero fuel related issues. I was running 91 octane gasohol when I took it to the drag strip.
Use the best gas you can find and don’t stress over it. I think using a good Top Tier detergent gasoline is much more important than scouring the planet for 93 non-ethanol gas.
Use the best gas you can find and don’t stress over it. I think using a good Top Tier detergent gasoline is much more important than scouring the planet for 93 non-ethanol gas.
MBWorld Fanatic!
Joined: Oct 2010
Posts: 5,142
Likes: 1,293
From: Southern US
2010 E550, 273 Engine: 2012 S550, 278 Engine
So, what about Direct Injection? These cars don’t compress air/fuel mixture entering in the cylinder as fuel is injected just before ignition, like spark is done. Perhaps just slightly before the spark. Doesn’t that take a big part of pinging scare away?
Super Member
Joined: Aug 2013
Posts: 779
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From: Texas
63 Falcon vert
[QUOTE=Arrie;8674881]So, what about Direct Injection? These cars don’t compress air/fuel mixture entering in the cylinder as fuel is injected just before ignition, like spark is done. Perhaps just slightly before the spark. Doesn’t that take a big part of pinging scare away?[/QUOTE
Good question. Direct injection is basically a 3way timed event totally controlled by a guru program. Air thru a valve, fuel from a jet and spark from a coil arrive on command. If any are out of calibration would there be a ping? I tend to agree with you but I need a beer, too.
Good question. Direct injection is basically a 3way timed event totally controlled by a guru program. Air thru a valve, fuel from a jet and spark from a coil arrive on command. If any are out of calibration would there be a ping? I tend to agree with you but I need a beer, too.
MBWorld Fanatic!
Joined: Aug 2014
Posts: 5,322
Likes: 1,678
S500
in the damp winter you don't want ethanol - in the summer you might want the extra performance of using the optimal octane rating for that vehicle
the ONLY reasons we have ethanol is two fold
1) its cheaper for them to make and you need to buy more to go as far as real fuel
2) car manu love it as it wears the car out, making metal tanks, pipes, lines and injectors rot out - yes plastics can now mostly cope and hoses designed to cope since 2000 ish (MOSTLY)
there is NO environmental benefits its actually slightly worse - its just marketing clap trap and theft why we are forced to use it....
on my BMW bike the difference from usable low octane fuels, to the real deal was light and day - felt like a 20% performance uplift throughout the entire range - even idle was smoother. A lot of UK bike mags are saying they can measure the savings of using the much more expensive higher octane fuels as the lower ethanol content extends your mpg by more than the high cost per litre
the ONLY reasons we have ethanol is two fold
1) its cheaper for them to make and you need to buy more to go as far as real fuel
2) car manu love it as it wears the car out, making metal tanks, pipes, lines and injectors rot out - yes plastics can now mostly cope and hoses designed to cope since 2000 ish (MOSTLY)
there is NO environmental benefits its actually slightly worse - its just marketing clap trap and theft why we are forced to use it....
on my BMW bike the difference from usable low octane fuels, to the real deal was light and day - felt like a 20% performance uplift throughout the entire range - even idle was smoother. A lot of UK bike mags are saying they can measure the savings of using the much more expensive higher octane fuels as the lower ethanol content extends your mpg by more than the high cost per litre
Junior Member
Joined: Mar 2016
Posts: 53
Likes: 8
2013 S550
in the damp winter you don't want ethanol - in the summer you might want the extra performance of using the optimal octane rating for that vehicle
the ONLY reasons we have ethanol is two fold
1) its cheaper for them to make and you need to buy more to go as far as real fuel
2) car manu love it as it wears the car out, making metal tanks, pipes, lines and injectors rot out - yes plastics can now mostly cope and hoses designed to cope since 2000 ish (MOSTLY)
there is NO environmental benefits its actually slightly worse - its just marketing clap trap and theft why we are forced to use it....
on my BMW bike the difference from usable low octane fuels, to the real deal was light and day - felt like a 20% performance uplift throughout the entire range - even idle was smoother. A lot of UK bike mags are saying they can measure the savings of using the much more expensive higher octane fuels as the lower ethanol content extends your mpg by more than the high cost per litre
the ONLY reasons we have ethanol is two fold
1) its cheaper for them to make and you need to buy more to go as far as real fuel
2) car manu love it as it wears the car out, making metal tanks, pipes, lines and injectors rot out - yes plastics can now mostly cope and hoses designed to cope since 2000 ish (MOSTLY)
there is NO environmental benefits its actually slightly worse - its just marketing clap trap and theft why we are forced to use it....
on my BMW bike the difference from usable low octane fuels, to the real deal was light and day - felt like a 20% performance uplift throughout the entire range - even idle was smoother. A lot of UK bike mags are saying they can measure the savings of using the much more expensive higher octane fuels as the lower ethanol content extends your mpg by more than the high cost per litre
MBWorld Fanatic!
Joined: Oct 2010
Posts: 5,142
Likes: 1,293
From: Southern US
2010 E550, 273 Engine: 2012 S550, 278 Engine
in the damp winter you don't want ethanol - in the summer you might want the extra performance of using the optimal octane rating for that vehicle
the ONLY reasons we have ethanol is two fold
1) its cheaper for them to make and you need to buy more to go as far as real fuel
2) car manu love it as it wears the car out, making metal tanks, pipes, lines and injectors rot out - yes plastics can now mostly cope and hoses designed to cope since 2000 ish (MOSTLY)
there is NO environmental benefits its actually slightly worse - its just marketing clap trap and theft why we are forced to use it....
on my BMW bike the difference from usable low octane fuels, to the real deal was light and day - felt like a 20% performance uplift throughout the entire range - even idle was smoother. A lot of UK bike mags are saying they can measure the savings of using the much more expensive higher octane fuels as the lower ethanol content extends your mpg by more than the high cost per litre
the ONLY reasons we have ethanol is two fold
1) its cheaper for them to make and you need to buy more to go as far as real fuel
2) car manu love it as it wears the car out, making metal tanks, pipes, lines and injectors rot out - yes plastics can now mostly cope and hoses designed to cope since 2000 ish (MOSTLY)
there is NO environmental benefits its actually slightly worse - its just marketing clap trap and theft why we are forced to use it....
on my BMW bike the difference from usable low octane fuels, to the real deal was light and day - felt like a 20% performance uplift throughout the entire range - even idle was smoother. A lot of UK bike mags are saying they can measure the savings of using the much more expensive higher octane fuels as the lower ethanol content extends your mpg by more than the high cost per litre
In the nordic countries a liter bottle of pure ethanol in a tank of gas was used to fight water in the fuel in winter time. I’m not sure if this is still done because they have ethanol mixed in fuel like we do but you absolutely do want ethanol in your fuel at winter time. Ethanol mixes with water keeping it from freezing and this mixture burns thru the engine.
What other ingredient would you recommend for this purpose?
MBWorld Fanatic!
Joined: Aug 2014
Posts: 5,322
Likes: 1,678
S500
there should never be water in the fuel - had to do the level sensor on my 13 year old bike last year - the inside of the tank was 100% clean good as new not a drop of anything you didn't want - some photos you see where they used ethanol its just a rotting mess of corrosion on the level sensor and pump
if there is an issue with water in fuel, the issue is usually the supply chain not the car, (you can test for ethanol by adding water shaking and seeing the two mix - google agrees its a way to try and mix so it gets burnt...) but for me putting ethanol in is effectively adding water and its also hygroscopic so its doing the opposite of helping any issues of water in the fuel
were they adding to tractor fuel to thin that rubbish due to waxing?
.
if there is an issue with water in fuel, the issue is usually the supply chain not the car, (you can test for ethanol by adding water shaking and seeing the two mix - google agrees its a way to try and mix so it gets burnt...) but for me putting ethanol in is effectively adding water and its also hygroscopic so its doing the opposite of helping any issues of water in the fuel
were they adding to tractor fuel to thin that rubbish due to waxing?
.
Last edited by BOTUS; Nov 27, 2022 at 08:48 AM.
