peeta123

i think that if you are planning to keep the car for many years then it is worth using premium gas. if you are leasing then you dont have to worry as much because you are going to be giving the car back to them.

g2k

I'm not sure why some of you keep bringing up saving money at the pump,I've been following this tread and everyone that saying its ok to use less than what is recommend are never saying anything about saving money or they use the lesser of the gas because they can't afford it,what I'm getting from what they are saying is the car will be ok if you use less than what is recommend or its ok but you will lose power or it will run less efficient ect.....so please stop it with the"don't drive a $60,000 car if you can't afford blah blah blah ......... thank you

pmb600

Well if they don't care about saving money then why ignore the instructions from Mercedes and use regular? I don't really see any other reason why someone would not want to use Premium.

g2k

I agree also,I also believe that some people who lease or rent these vehicles feel the same way and use less than what is recommended ,I know a lot of people buy these vehicles used and never heard that they have to take a vehicle back or change anything because someone use less than recommended gas in it ,not just for mb but for any car that requires a higher octane gas and less is used

g2k

I can't speak for everyone but here is an example, I can afford to sleep with my television on all night but choose not to because it would be wasting money, not that I can't afford it but why spend it if you do not have to

pmb600

I agree there is no point in wasting money. This is not a case of wasting money, because the car clearly requires premium to run properly, so this is not equivalent to your TV example.

Tjdehya

It is not RECOMMENDED! It is REQUIRED!
The only reason why someone would put 87 in their car when 91+ is REQUIRED is because they are CHEAP.

g2k

If you remeber you had said somomething about if you cant afford to drive a $60,000 car bhah blah bah and i said its not about saving money but wasting it.... then you said i cant see why else they would put less than what is REQUIRED if they are not trying to save money or cant afford it.... then i said my tv example about wasting money.... so with that said if someone believes that the car doesnt need 91 in their mind they would be wasting money which goes back to my example,that makes perfect sence if you understand what im saying

RNBRAD

This is exactly how misconceptions start. The car will run properly, it won't damage anything. It's not about "well I plan on keeping the car so I want to run premium as to make my engine last longer", yada, yada. The engine will last just as long if not longer. You could pull the motor apart at 200k and no one would ever guess you used 87 vs 91, 93 or whatever. The higher the octane doesn't mean the gas is superior when in fact more times than not you get bad gas from the higher octane tanks than regular cause it sets longer and turnover is slower allowing more time for the gas to loose octane, it oxidizes and becomes stale.

I'm not saying there isn't benefits of using premium unleaded in our engines, but I guarantee motor longevity and trouble free performance is not one of them. Quite frankly, the MB motor could care less where the timing is set at. It's just like race motors. We would advance or retard (manually) our timing depending on what RPM we wanted peak power. We would just match the gas to our timing, made no difference. Our cars do the same except it (automatically) selects the proper timing for the gas being used. In actuality advanced timing is harder on a motor than retarding it. You have higher cylinder pressures during combustion which is harder on pistons and rods in the long run. So I would be willing to bet that a person could get more miles from lower octane gas than premium. So when a person says that 87 will ruin this motor or shorten it's life, I say marketing has got the best of them and they don't understand motors. Just like Harley owners and using Harley branded oil. They swear anything else will ruin their motors.

fwiw: I do use premium in my 212 e550 but I've never used it in my 2004 e320

g2k

recommended!!!! because if it was required it wouldnt run on anything else ,example if you buy a bluetec mb it REQUIRES diesel if you put anything else in it, the car it will be damaged fast... not over 4 or 5 years+ but now .......WHY???? because its required diesel..... get it now

g2k

ahh.... thank you.... someone that thinks straighti couldnt have said that better if i had to!!!

pmb600

Yes I do remember saying what I did about the price of the car and I stand by that whole heartedly.

You say "so with that said if someone believes that the car doesnt need 91 in their mind they would be wasting money..." I'm sorry but it's not about what one individual person may think, the car requires premium. It states it on the inside of the gas cap, it states it in the operator's manual. Not sure why you think this is just a recommendation.

Tjdehya

Wow, you are not very smart are you? For your car to run the way MB intended... it is REQUIRED!!!

Pntblnk

TJ - suggest you start presenting your side of the debate with FACT's rather than personal insults, it makes for a much more compelling argument.

The consistent points I read being made are "it states in the manual as REQUIRED...." and "MB says...." is is the technical writers that compose compose the manuals and marketing folks approve the final copy. It is not the chief engineer for the power train module. If a marketing product manager thinks they can get an extra 1% of margin by stating "required" VS "recommended" they will certainly go with "required".

This is an active debate on many public boards and one that has as many pieces of evidence / theory to support either side. Let's just stick to facts rather than name calling.

I am still running 93 in my 550 as previously stated but enjoy hearing a compelling argument from both sides.

g2k

like i said if it was required it wouldnt run on anything but 91 or higher its recommended or else it wouldnt run at all,dont get your panties in a bunch and start calling names because my example made sence and all you can come back with is "for your car to run the way mb intended" crap

g2k

Thank you ...i thought it was a little childish of him to start calling names

Arrie

It is so funny to see all these posts about a simple thing. How many rreally knows why 91 min octane is required by MB when the car surely runs with 87? Anybody guess?

g2k

i cant understand why your not getting what im trying to say, in tread #53 you said "Well if they don't care about saving money then why ignore the instructions from Mercedes and use regular? I don't really see any other reason why someone would not want to use Premium".... my answer to that is..... "if they believe that their car can run on less than 91 then in their minds they are wasting money.." it doesnt matter what mb recommends or requires because they believe that the car runs fine on less then 91.....therefore they are wasting $$$$get it NOW????

ohlord

Idiots?
Read your owners manual. Engine damage can result,limit loaded driving conditions,limit speeds,it is all listed in your owners manual.
Even the part about engine damage caused by lower than required fuel can void your warranty.

You need not guess as to why it will run on 87 but requires 91
It is a high compression engine. Sure the ecu will take the input of the knock sensors and dial back power but at some point under load you could toast a piston.
The moron that states a high compression engine running low test will outlast the same engine running high test ,doesn't know squat about engines

Cheap is the only reason people keep bringing this up and every time gas goes up a dime the cheapasses come out of the woods.

Make sure that you advertise you ran nothing but low test in the car when you sell it. I am sure you will get plenty of good offers

Case rested
insults warranted

pmb600

You don't have to be so hostile. And try writing in full sentences and then maybe we can understand you better.

I will never agree with your point of view on the subject, and I think it's rediculous that a bunch of morons think they know more than the engineers who design the car.

K-A

I'm standing by this argument as well.

I'll admit when I'm being "cheap", and it happens quite a bit (and I'm proud of it!).

If you are putting in 87 when the car says that it REQUIRES 91, you are intellectualizing in your own mind, why the engineers are misleading you, and you're going on your own bases and theory as to why 87 is fine (and of course research, studying, etc. in some cases).

Why? To save at the pump, because you don't want to spend the money on 91, period. If that wasn't an issue, you'd just use what the manufacturer requires.

Arrie

Look guys,

Even MB says 91 octane fuel is required it does not mean that 87 will cause damage to the engine. I think MB is saying 91 or higher is required because with lower octane the car will not meet adverticed HP and mpg numbers.

If fuel octane is too low and premature ignition would happen the ECU retards the spark. I also believe that it chokes the throttle as if the ignition happens before the spark it means that retarding the spark will not prevent premature detonation, i.e. less air must be allowed inside the cylinder. This, of course, means that less fuel can be burned and the engine now needs to operate at a curve, which is not the optimum it was designed for.

Premature detonation will not ruin the engine, just takes power away. Normally, when everything happens like it is designed to happen detonation occurs when piston is all the way up or actually before that. This means burning and expanding gas inside cylinder occurs at minimum available volume in the cylinder and so gives the piston the biggest jolt to keep going down. If detonation happens too early it just means some of this kick directs against rising piston, which means the pressure from fuel burning would work opposite than what is meant to be.

Almost all the talk about low octane fuel ruining the engine is carbage. Low octane fuel just don't give the same output from the engine as the high octane that it was designed for.

It is quite common to see premium 91 or 93 octane fuel cost just about 10% more than regular 87. People who don't believe me do the test and be amazed.

Fill up with 91 or 93 and drive and calculate the real mpg. Don't go by the number car tells because it is not true. Fill up the same way every time, i.e. if you give it two klicks after first shuts off do the same each time. Run at least 3 tankfulls.

Do the same with 87 octane exactly, i.e. try to drive the same way and equal amounts of highway / city.

The result of this test is that with 87 octane you will get 10% less mpg or even less than that. If the 91 or 93 octane is real and 87 is real this is what you will find out.

There is no savings running 87 octane vs. 91. Fuel cost per mile is just about the same but you will lag some performance with 87 octane.

For those low octane runners doing this test remember not be stepping on that pedal any different than you do with 87 in the tank. It easily happens when you see and feel this car can actually go too...

K-A

Perfectly put.

I'm not worried about it "ruining" the engine, as I know the engine will compensate, and be fine. I have two worries: 1- You're not getting your optimum performance, efficiency, and emissions, and 2- You're not saving ANY gas, possibly even getting worse gas mileage. So why would anyone put their engine at a lower and worser operating form, and consume possibly even more gas, to save a few measly cents at the pump? It baffles me.

Tjdehya

Hey, I bet you car will run with just 1 quart of oil too...
Hey, screw the maintenace schedule.
Hey, pfft... 32 psi in tires?!? for what? it will drive just fine with only 10psi!
Hey, engine coolant? please! its like 20 degrees outside.

OMG
Hey, those dumb German Engineers have no Idea whats good for the car!!!

K-A

G2K, just put in what's required, and spend the extra $2-$3 a tank. Undermining the M-B engineers means you're working too hard to convince yourself of something.

This ain't a Nissan, Toyota, or Honda ().