jturkel

and AZ lol. wish we would get REAL 91. not the octane tested 87 that they claim is 91

220S

fwiw, I normally use Chevron 91 and once in awhile add some Techron.

But there are three 76 stations in my neighborhood (and more a bit farther away) that sell 100% octane. Once in a while I've done a mix of 91 and 100.

No difference in performance that I can really feel, but I do get better gas mileage.

ps, that thing about cleaning the gunk out of the tank from Shell 91 sounds like a dealer's crock of sh*t, sorry.

MB_Owner

I took a look at the 2010 online Owner's Manual and it makes no differentiation in octane rating requirements for the AMG version...minimum of 91 (PON) for all US spec engines.

"Fuel requirements

Only use premium unleaded gasoline. The
octane number (posted at the pump) must be
91 min. It is an average of both the Research
Octane Number (RON) and the Motor Octane
Number (MON): (RON+MON)/2. This is also
known as the ANTI-KNOCK INDEX.

Reformulated gasolines (RFG) and/or
unleaded gasoline containing oxygenates
such as ethanol, TAME, ETBE, IPA, IBA, and
TBA can be used provided the ratio of any one
of these oxygenates to gasoline does not
exceed 10%; MTBE must not exceed 15%.
The ratio of methanol to gasoline must not
exceed 3% plus additional cosolvents.
Using mixtures of ethanol and methanol is not
allowed. Gasohol, which contains 10%
ethanol and 90% unleaded gasoline, can be
used.

These blends must also meet all other fuel
requirements, such as resistance to spark
knock, boiling range, vapor pressure, etc."

So I'm curious to know why the AMG fuel door sticker would specify 93?

Further, I see SoCal's largest AMG dealer, M-B Long Beach specifies 91.

Lastly, I found nothing in the Owner's Manual mentioning a need to flush the gas tank periodically when using lower-octane gas in emergencies. Looks like unnecessary dealer profit to me.

Quadcammer

I'd love to hear your explanation for this.

Running higher octane than your car is tuned for is simply a waste of money. Unless you are running leaded fuel (typically above 104) will greatly reduce the life of your 02 sensors and cats. In addition, high octane race fuel has a different stoich a/f than typical pump gas.

Running 100 octane on a stock C63 will not damage the engine, but its a waste of money and will most likely cause the car to generate LESS power.

desmo996

Great research!

Then the mystery is ultimately why the owners manual contradicts what the sticker on the fuel door says. Which one is accurate for this car, a minimum octane of 91 or 93? The owner's manual explanation does seem more in depth.

skoobz2001

Necropost!

I'm in Alberta, Canada and it's very hard to come by anything higher than 91 octane. Certain gas stations have 94 octane, but it contains (I believe) "up to 10% ethanol".

Gas nerds - would it be better to go with the blended 94 or the 91? Typically, I run Shell V-Power 91 (but I've only filled up my UberBeast once so far)...

RobertG

if you use low octane fuel instead of what the manufacturer call for,it will lead to serious engine problems down the road.
Preignition is going to damage the pistons, engine computer will retard the timing but not enough.
Low octane fuel burns faster then high octane, when the cylinder is coming up on it's power stroke, fuel is introduced and it ignites too fast causing the piston to rattle in it's bore(piston is still traveling upwards while the combustion is trying to push it down) as well as damaging the piston ring lands.
low octane fuel gives you less bang for your dollar as well ,by causing you to press the throttle little more to achieve the same performance using high octane fuel.

Sincity

OP just disappeared.

Mort

In Canada the octane rating is an average of RON/MON and 91 Octane is the minimum posted octane rating for Premium unleaded gasoline as required by MB. Shell V-Power 91 is acceptable for use in the C63 and is good quality gasoline.

The 93 min. on the fuel door is for RON rating only and it is a higher rating used in Europe and other places but not in North America.

gsrjc

So in Maryland, Sunoco has 93 and 91 and I put 93 in the C63 but for my other cars like the ML and GLK which need premium gas, should I just put in 91 instead of 93?

skoobz2001

Danke!

Swiftler

Question. If you see two gas station side by side: Shell and Petro Canada. Which gasoline would you use? Shell V-Power 91 or Ultra 94 on the C63?

derspi

^^

Really?! Flip a coin if you can't make up your mind.

Mort

In North America 91 octane is the minimum posted rating to run in vehicles requiring Premium Unleaded gasoline. In some states and areas it is he only Premium octane available. Yes if you want to save a buck and don't need every possible ounce of power you can get then 91 Sunoco will do fine in the ML and GLK or the C63 for that matter. If I had the option that is what I would do I expect with 93 in the C63 and 91 in the ML and GLK. That is the only option we have here so I have no other choice locally except to run 91 in the C63 and it seems to run fine.

I run Shell when I can because I think it has a better additive package than other local New Brunswick stations and try to buy from higher volume stations and hope the gas is fresher with less chance of contaminants and water in the tank.

ZephyrAMG

I see a lot of 93 here in the Midwest...of course not west coast.

MiamiAMG

Here in Miami, the highest rating we have & the only one i use is 93 octane.

Mort

We do not have Petro Canada Ultra 94 here AFAIK so I am not sure. We don't even have a convenient Petro Can station so I never use or consider it. If you try the Ultra 94 and do not notice any difference then I would save the dollars (if any) and use the Shell V-Power 91 for DD. I don't know much about the quality of Petro Canada gas but up to 10% ethanol can be used. I am not sure I would use it if I had other options.

Nstar

No, you're fine with 91 and no damage will come from using it and no cleaning necessary. 93 is preferred but if you're worried just keep a fuel can and add a couple of gallons of race gas (100-110) to each tank full. Also, bare in mind that in a pinch you could use 87 (like a 1/3 of a tank to get you to the next gas station) and it wouldn't hurt anything long term so long as you didn't make a habit of it.

I'm just glad someone posted about the differing fuel ratings between the US/EUR/AUS. This must be one of the most discussed auto subjects on the internet and all the information is already out there.