Hello Good people,

Please forgive if this question has been asked before. But I have been in a debate with a few people about premium vs. mid grade fuel for my car.

I only put premium fuel in my E350, because I love that car and want to treat it well (like the fine piece of machinery that it is), and that is the suggested octane level. Now I don't' need to fully understand "combustion rates" and all the reasoning behind it.

I just would to know your opinion and if you use premium fuel for your E or not.

I've been told by a few people that my E isn't a High Performance vehicle and could easily survive on mid grade.

Thanks in advance for your thoughts.
Kellie

 

Mercedes says 91 octane minimum. Thats what should go into it. Period!!

 

Thanks sosh. I agree with you. Treat it like it deserves to be treated!

 

My best friend has been a benz mechanic for 15 yrs and has always run mid grade in his cars and recommended I do the same. I have done the same as well with both my cars.

 

Of course it will survive, the car's ECU will adjust timing to the octane. But the recommended RON will give you the optimum performance your motor was designed for. And the additives in brand name gasoline (Shell, Chevron, etc..) are important to the long term health of your motor (carbon buildup, etc..) Why try to save a few pennies this way?

 

I guess your 15 year mechanic and you are more knowledgable than the engineers at Benz who developed the engine and came up with this requirement. Certainly would not like to purchase your car when you sell it nor would I care to have your good friend turn a wrench on any of my cars.

 

you're not damaging the engine with mid grade but you are reducing horsepower and potentially causing more deposit build up. With mid grade the car has to adjust its timing much more regularly and you'll probably notice knocking or pinging when the engine is under stress - i am interested to see if this is the case.

I use premium in my e550 because I tend to drive a bit aggressively and want all the ponies to be there when I ask for them.

 

Guys, really add up the differences in how much you'd save in the year based off of the .10-.20 per Gallon via lower Octane.

There's a reason they say to put in Premium, and Benz certainly isn't gaining revenue from fuel usage, and certainly not helping themselves out by asking customers to shell out more $$$$ for Gas.

You buy a premium car, abide by its fuel requirements. Or at least do it so the guy who gets it after you, who might be a person who likes to pamper and care for/keep his/her cars for a long time, gets a good/well kept example. Problem with the Leasing generation, is no one owns their cars anymore, 90% of New Cars on the road are Rentals, long term "Hertz" cars practically, so naturally, most people won't really care.

 

Is that an accurate number or are you just being hyperbolic? Not trying to argue, just wondering.

 

Not not accurate at all, lol. Just being dramatic for the sake of a point.

I actually don't know what it really is. In SoCal at least, I'd wager that seems a very realistic, if not conservative number for Luxury Car buyers.

 

Its more like 25 to 30%

 

Its the knocking and pinging that causes severe internal damage to the engine. Stuff like holes in pistons and valve issues.

 

If the pennies in extra fuel cost are a factor, you bought the wrong car. You don't feed a dog cat food.

 

HI Petee - not concerned about the difference in price of premium vs mid grade. I only use premium, but some people keep making comments to me about how that car isn't high performance and it's a waste. I researched this car prior to buying it and knew before I bought it that it will cost more to maintain and not trying to skimp at all.

Thanks for your help!

 

+1.....You drive a Merc, why be cheap over a couple $$ sacrificing performance.....

In this case you're better off driving a KIA...




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I use premium for all my cars. May as well get the best fuel available especially since difference in cost is negligible. It can be argues premium fuel gives you more mileage anyway. So net-net, its a wash. Also isn't US fuel supposed to be inferior to European fuels? I read somewhere that there is more sulphur- reason given why the 2010 E-class engines are carry overs from the outgoing models. This is not the case in Europe, where the 2010 e-classes got brand new engines.

 

I guess you can use what you want, but if you feel it will somehow harm the motor maybe you should put a little more faith in MB's technology or learn more about it. I had saved the quote below from when I bought my 04 w211 and it has had nothing but mid grade put in it since I bought it and never a ping or a problem.

"Today's engines use highly evolved versions of a device called a knock sensor to adjust settings automatically for low-octane gas. And more engine control computers have adequate memory to allow separate sets of instructions for various octanes. The engine control computers keep pushing to maximize performance on whatever grade of fuel is used.

Extreme pressure inside the cylinders causes knock, which is the sound of the pistons literally rattling inside the cylinders. Too much too long can damage the engine. A little now and then won't.

The only modern engines that should really need premium are those with superchargers, which force-feed fuel into the cylinders. "You're driving along and just tramp the gas and the knock sensor cannot sense the knock fast enough in some cases," because the supercharger boosts pressure so fast, says Bob Furey, chemist and fuels specialist at General Motors.

Burning regular when the owner's manual specifies premium won't void the warranty, nor damage the engine, even the most finicky automakers say. "You're giving up perhaps just a little bit of performance that a customer wouldn't really even notice, it's so slight," says Furey.

Automakers say they don't test premium engines on regular to check the difference, but some auto engineers estimate that power declines roughly 5%.

"We can't guarantee the vehicle will perform as specified if other than premium fuel is used," says Mercedes-Benz spokeswoman Michelle Murad. All U.S. Mercedes engines specify premium.

All Porsche engines are designed for premium, too, but it's not available everywhere. "Our cars must be able to drive all over the world, and so we are able to run on regular," says Jakob Neusser, director of powertrain development at Porsche's research and development center in Weissach, Germany. "You don't have to feel that a mechanical problem or anything else will happen" using regular gas, even in the highest-performance, regular-production Porsches."

It's a good entire read if you wish http://www.usatoday.com/money/autos/...emiumgas_x.htm

 

Yes you do as you please but you are off track on the requirement whys and wherefors. The knock and ping is caused by detonation of the fuel before it should explode. A knock sensor senses a knock after it happens and retards the spark but that also reduces power. That one knock does not always hurt anything but when it happens consistantly where someone always runs substandard fuel all the time it does damage. I believe this is called pre detonation and that can shatter a piston eventually. In addition the higher heat of the pre detonation can cause a myriad of other issues over time. A supercharged engine by the way typically has a lower compression ratio than a normally aspirated engine. It is the compression ratio that drives the octane requirement. In a supercharged engine it is the cylinder pressure caused by the boost of the supercharger that drives the requirement. In jet engines (as an aside) one can burn gasoline in a pinch BUT the burn must be recorded in the aircraft records and it is permitted only for a certain number of hours between overhaul periods without reducing the time between overhaul. So get your facts straight

 

You must of missed the point or didn't understand the article. I build race engines, I totally understand pre-ignition and octane requirement as well as anyone. I have to check each pistons compression requiremens after a build to assure I get the right octane gas as not to destroy a motor I just built. Thing is the motors I build have set timing, not variable with memory. I also understand the technology that prevents preignition. Middle grade fuel is not substandard fuel, it is fuel that is less resistant to preignition than a premium fuel, less flamable in lamens terms. Understand that these cars are not preigniting, you know combusting before the piston reaches TDC causing a ping. It's not happening because of the exact same technology most all manufacturers use in their cars today. How many engines you hear of today being riuned by preignition?

 

I feed my cat dog food.

 

If the cat barks, you're feeding him the right stuff. Furthermore keep the cat indoors when the neighbour's dog is in heat.

 

I have used premium in both E's. Using a lower grade fuel will lower performance (the ECU has to retard the timing to accomodate a lower grade fuel) and for the same reason you will notice somewhat lower fuel economy. Spring for the extra and put into the car what the manufacturer recommends.

By the way, I lease my cars and do not have the mentality that I do not care because I don't own it. If that were the case, I wouldn't hand wash it and not take it to the car wash unless absolutely necessary. I lease for business reasons and so that I do not have one of these babies without a warranty.