boater07

Is there are benefit to use highest premium vs the 91 midgrade?
My salesman suggested any 91 is ok in E350

ghstudio

As I understand it, octane ratings are rough estimates. Octane rating measurements differ...some are measured at the bulk storage tank, some are measured at a gas station tank, others are measured other ways. All 91 octane is not the same, any more than all 87 octanes are.

Your car will run fine on any premium gas....you don't have to search for 93 octane. In fact, your car will run pretty darn well on mid range 89 gas if you live in an area that's flat and you drive conservatively. If you floor the gas or accelerate going up long hills, then it's premium all the way.

hyperion667

I always get the 93, and have since bringing the car home....
I even filled up the loaners I've had with it....
but I wonder about the "may contain 10% ethenol"
on the pumps

xolinlevh

I usually use 92, the station a block from my house has it, but if im not at home, 91 is fine. Ive wanted to try 95 or 100, but its so hard to find anyplace that sells in here =/

BenzV12

Fuel sticker recommends 95 octane (US varies ),in English not the highest available in a sense .So, I haven't tried 97 or premium yet but I should because performance kit recommends higher octane than usual

samkimg

I just try to be consistant with my gas purchases. I look for the premium gas from the same suppliers that I trust to have high turnover of fuel, and that keep their fuel filters fresh. I've never tried anything over 91 octane, simply because I can't find it anywhere that I have driven.

CEB

The US rates octane by anti knock index (AKI) while Europe and most others rate their gasolines by RON (Research Octane Number.) A RON of 95 in Europe is equivalent to a AKI of 91.

Our cars require an AKI of 91. There is no advantage or running an AKI of 92 or 93 - the car won't run better and you're just wasting money. An AKI of 89 is pefectly fine in high altitude states like Colorado.

Other posters have discussed how lower octane gas may affect gas mileage and knocking but 91 octane is what you should be using in most of the US.

RNBRAD

87 to the highest un-oxygenated unleaded fuel you can find (100 OR SO?) will run fine in your Benz. Higher octane fuel rating will benefit the Benz only to a certain degree and that degree is usually what the manufacturer recommends, which is 91. Anything over that is a donation to the gas/oil company. Lower octane will effect your motors efficiency and performance but will not damage your motor.

Know that an ECU can compensate for lower octane but cannot compensate for higher octanes unless it is remapped. So like I said, absolutely no benefit in running a higher octane unless your car was designed for it ie. advanced timing, higher compression. This is why racecar teams measure and mix the fuel to the exact octane requirments just before the race to eek out every last ounce of HP the motor was designed or regulated for.

speedgoat

I use regular unleaded at the cheapest gas station I can find. I see no reason at all to use anything diffrent.

mbuster25

If 93 is avaiable, that is what I put in.

newyorktoLA

I use 91, which at gas stations around my area, is the highest I can get...however, whenever I get a loaner, it's regular unleaded all the way
You can't get over 91 in California for some reason...

alanme123

Im in Southern California and I have not seen anything over 91. I only go for Chevron too. They might be a little more expensive but i've had problems with some other brands.

listerone

I always use......diesel.

dfordham

Am I right in presuming that engineering quality was one of the reasons you bought an MB?

If so, why would you want to second guess the engineers' recommendations?

Regards,
Don

listerone

Yikes! The two most recent gas powered cars I've owned were both Infinitis.Both had Nissan's famous 3.5 litre engine.The owner's manual of both clearly stated that Premium was *recommended* for maximum performance but the use of 87 was allowed and would result in no damage to the engine.IIRC,there's not a Mercedes sold here today that does not *require* Premium and doesn't warn that the use of anything less *will* result in damage.

Sounds like it's a penny wise,pound foolish attitude...particularly if you lease.

bigh123

What about Plus instead of premium? Some people mentioned that would be alright.

newyorktoLA

listerone

First,I'm absolutely no expert on such matters.If I wasn't too lazy I'd reach for my owner's manual to see if I'm correct about "premium required"...in my car,at least.If,by chance,I was correct in making the blanket statement I made earlier then it seems to me to be beyond silly to tempt fate in order to save a few bucks a year...particularly with such an expensive,well engineered,car.

Hey,just my 2 cents' worth...

El Cid

Here we go again. 91 octane is REQUIRED. Anything less and you lose power and MPG because the engine does not run as well. If M-B could say use 87 or 89, they would have. Using regular gas is a selling point for cars.
Think how much you would save if you got rid of comprehensive and collision insurance on your M-B!
As regards ethanol, it is in almost all gasoline today at 10% and the ethanol/agri-business industries are lobbying (paying off) Congress hard to get it raised to a mandatory 15%. You can still find a few stations that will sell non-ethanol, but generally at a substantial mark-up.
The "bio-diesel" industry is probably even bigger.
There is a small tank farm near me and they bring in 100 railroad tank cars per week just to add 10% ethanol to the tank trucks leaving it. Planning to expand to 150-200 per week.
Instead of posting here, e-mail your Congressperson and Senator and ask them to remove all mandates and subsidies for ethanol.

Arrie

Finally someone else speaks it out like it is. Lower octane fuel can be used but performance is lost. It will not damage the engine.

I use higherst I can find, which is 93 but it is very easy to feel how fuel from even some big name oil companies is not what the pump says. I have found that I can get better quality gas from some "third party" stations like Murphy or Race Trac. Yes, seriously. And one chain CITGO, which some perhaps don't like to use, seem to have in their pumps what is adverticed.

Gas cost using different octanes is about the same per mile. With lower octane engine performance is lost so is mpg value lower. You lose the lower price at the pump in lower mpg on road but you also lose big portion of power. It is very noticeable between 87 and true 93 octane fuels.

Arrie

Why are you so strongly against ethanol mixed in the gasoline?

CEB

Names of gas grades vary by station so plus means different things.

What is so difficult to understand about "91 octane required?" 91 is not 89 or 87 or 85. 91 means 91.

If you use 93 you are not doing any harm but you are flushing more money needlessly down the drain. Using 89 won't make your car explode but it will return worse gas mileage and could cause issues if used exclusively.

I've used 87 octane on a cross country drive when I drove up to a station on fumes and all they had was 87. It was those 20000 miles on I-70 through Kansas so I could have probably poured water in and it would have run.

dfordham

Is this personal opinion, or do you have references to support this? If so, we might have a class action lawsuit against MB!

Regards,
Don

Fung63

the OP's question is easy to answer. At the gas pump, you press the fuel choice button with the highest number on it

as a side note.. Esso here in Canada only has 91 as its highest.

telemakhos

My mechanic told me that there is no point in putting anything higher than the 91 that MB recommends. As for ethanol, he told me that too much is a problem since ethanol is corrosive. Years ago I asked MB Canada directly about fuel. I'll have to dig up their answer but I remember something along the lines of not exceeding 10% ethanol.