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Does it make a difference to use a higher octane fuel? I have an 89 300e and I normally use 94 octane. when its get really expensive I use 89 octane. I know the manual says you have to use premium gas..what does that really mean?
 

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95 E320
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my manual says at least 91. I am gonna stick with at least that high. Doesnt your car start knocking or something if you dont use the correct gas...oh maybe some wives tale.. You can see I dont know much about cars..just follow directions. sorry im not more help
 

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2001 E320; 2002 ML500
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If you use 87 you will consume more fuel and run poorly.
Stick to 91 octane or better.

Sergio
 

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2004 SL55 AMG
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[8D]

Hi T,

This topic has been kicked around the Benzworld forum and others a lot. Here's a link with everything you ever wanted to know about octane, and more:

http://www.prime-mover.org/Engines/GArticles/octane.html

Because US pump numbers average research and motor methods and say nothing about sensitivity, it's hard to know exactly what you're going to get from any supplier. Regional differences count. My advice is, don't run anything less than 89 octane if you buy from a major brand and 91 octane if you buy no-name gas.

The fact that you don't hear any knocking does <b>not</b> mean you aren't causing damage. The knock sensor reacts very quickly, but every time it does, some small amount of damage has already been done. It adds up.

Cheers!

Dave
 

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1990 300E, 2002 ML500
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sigh....


The reason manuals specify an octane to use is because the engines in certain cars have high compression ratios. Octane refers to how unexplosive a gasoline is, thus how much is can safely be compressed. If you use lower then 91 octane you will cause premature detonation in the combustion chamber, which can cause damage if it is not stopped. The frequency at which lower octane fuel will detonate prematurely depends on vehicle load and RPMs. Some newer, most I believe, engine have a program built into the ECU (Engine Control Unit) that will retard the engine timings if it detects lower octane, however the W124 is not equiped with such a program. So while purchasing cheaper gas may seem to give you some instant savings it will damage the engine over time, degrade performance and gas milage.
 

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2004 SL55 AMG
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505 Posts
[8D]

Hello Happy,

Unless my mechanic is mistaken, and I doubt it, my W124 does have an electronic knock sensing system that will retard the timing when knocking is detected. Hell, even my 1988 Ford Taurus had it. Wasn't innovative at that time either.

Of course, I burn brand-name premium because at 10:1 compression, the motor needs it to prevent detonation at high RPM, not pre-ignition. For the whole story, read the article I pointed to, above.

Cheers!

Dave
 

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Just one more thing to add. Try buying gas fron name brand service stations. Personallty I use Chevron because of all the good additives and detergents they add to their gas.

I've driven gas powered Benzes in excess of 250k miles and never had any problem with carbon deposits, or anything else like that.

I used to work in the gas and oil field and trust me, not all gasolines are the same--even though initially they may all travel along the same distribution pipes.

With gas prices inching up it is very tempting to want to save a few pennies per gallon. It is, however, a false economy. If you want to improve MPG, check your tire pressure, make sure that your front tires are properly aligned, don't cary extra weight in your car, change the oil often--you can do all of these little things to improve MPG w/o having to resort to using cheaper gas.

Good luck!
 
G

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G'day all

I run 95 octane in my 300SL M103. I costs a bit more, $1.30 per litre, against $1.20 for 91 octane. I find the car runs a bit better on the higher octane, with easier starting and better topend. How much are you guys paying for fuel?

Andrew
 

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2006 S500 AMG Wifes Rig Hillbilly Girl 02 ML320
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Bigblue has been runnin on Reg gas for over a year now! No pings sputters or poor milage! The ECU seems to be doing what it's suppose to do![;)][;)][;)] I am not going to make the oil companies any richer than I have to![:(!][:(!]


Smokie
 

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mercedes w124 260E
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i pay arround 1 Euro per litre and my incomings are arround 200 Euro per month but i dont complain. so everybody let`s pour big money into oil companys pockets to get them richer that they all ready are[:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!][:(!]
 

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2004 SL55 AMG
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[8D]

Hi Smokie,

I hope for your sake the ECU's program is 'smart' enough to have set the spark timing back more or less permanently. Are you sure that is the case?

If the ECU resets the timing every time knocking is detected, you are putting premature wear on all the parts affected by detonation and/or pre-ignition, bearings being the most likely victims. Remember, just because you can't hear or feel the engine knock or ping doesn't mean it isn't doing so momentarily.

Best Regards,

Dave
 

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In Kentucky we are paying about $2.79 for 91. It spiked to $2.89 last weekend for no known reason other than the price monkey farted but has settled back down. I drove to Buffalo and back and prices were within .02 the entire trip. I took the Bimmer and got 32mpg.
 

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Good old supply and demand. In California, home of several large oil refineries, I just paid $3.05/91 octane at a Chevron Station.

When I drive to Santa Fe, New Mexico, gas is considerably cheaper throughout my whole route (I-40 to I-25). Except for some truly out of the way places around the MOjave Desert, gas is fairly cheap. Even in Santa Fe, which tends to be pricier in most htings, gas is still cheaper than in So. Calif.

Damned supply and demand.

BTW, thanks for your advice inthe "Painting question" thread. I may just do that. For the most part the paint is thick and glossy. The car does not have clear coat and, in So. Calif, that is a blessing. The sun and the smog here eat through clearcoats.
 

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1993 300SEL (Sold) 2007 X5
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I dont want to hear your crap about how high fuel costs are I'm paying $1.62 per L of 98 and 91 is $1.55 per L.[:(!]
 
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