red308

My 2008 CL63 has a sticker on the gas cap that indicates 93 octane minimum.
I know there are several states in the east and south that this is normally available. However, it is not available at all in most western or Rocky Mountain states.

Has anyone ever done a comparison of the performance with 91 octane vs 93 octane? Can you notice the difference? My car runs ok on 91, but it is very annoying to think that I am giving up some amount of horsepower because I can't get the correct octane level?

By the way, my MB dealer had no idea why this sticker is on the gas cap. Also, the MBUSA central phone helpline had no idea either. They all just say to use 91 octane.

Any comments on any of this would be highly appreciated.

MB_Forever

I know it sucks big time I too hate that I can't get 93 octane here in california, especially with all the crappy gas we have here.... just pitiful

All 63 engines indicate 93 octane is the minimum requirement while almost all other mercedes vehicles state a minimum of 91.

The 63 models are tuned for 93 not 91, so yes you lose a little performance but probably not much. A couple of people have experimented at the track with this. They ran their cars with 91 octane, then with a mix of 91 + 100 (mixed it with a ratio to get 93), and the same car ran consistenly faster and 2 to 4 mph higher trap speed.

If you can get 100 octane, you can obtain 93 to 94 octane by mixing 5 gallons of 100 with 15 gallons of 91 octane.

DFW01E55

You can run 89 and the ecu will adjust for it.

The higher octane gives better gas mileage and better performance.

WSH

Wouldn't be too concerned....

ECU's adjust vs octane; the claimed octanes at pump are imprecise anyway.....and, if concerned re: microscopic perf diffces vs octane, need to also consider decay curves of these 20" perf tires/wheels (micro-macrodeformations)/brakes in use on normal, imperfect public roads/twisties....prob need to get a new car every 5K mis to have near-optimal factory-spec chassis specs....

Suspect CA is easily world's largest single mkt for 500hp+ cars, so AMG and Ferrari are likely familiar w/adapting engine perf vs CA fuel (and chassis vs imperfect CA roads)....

Besides, in ex-CA locales, guys need to drive cars on those girlie winter wheels/tires for 5mos/yr; have notably slower fwys and onerous speed enfcmt...and/or endless boring, flat/straight roads.....

Net, net....I'll live w/CA fuel's 91 oct vs trying to enjoy driving any cars in ex-CA settings, no matter oct....

STEALTHBOMBER

order a drum of 100 ctane or higher from VP fuels and when you want the extra power just fill it up

red308

OK. I found a VP gas station about 1 mile from my house. (Lucky)

Am running some tests....

First test is I mixed their 93 Octane gas with equal parts of 91 Octane. I definitely noticed a slight increase in smoothness and power. Me likey.

Next test will be to do the 100 Octane mixed with 91 Octane to get a blend of at least 93. Will let you know what happens.

Btw, I have driven and restored many cars including Corvettes and Ferraris.
I had a 2001 Vette that loved the 100 Octane blend and it felt like it got me another 30 horsepower! I ran my 66 big block Corvette on the 100 Octane stuff and it was crazy fast.

Any other observations would be appreciated.

Clk&Slk

Mercedes probably put the wrong label octane rating for the European instead of the US. People that can get 93 octane can switch the fuel and timing setting in the ECU to take advantages of more power. In some European country, you can get up 98 octane.

Moviela

I would believe the Pope was Jewish before Mercedes put an incorrect label on a car.

The octane ratings on European gas is measured on the Research Octane Number (RON) scale, where in California pumps show the average of RON and the Motor Octane Number. An Octane of 91 in Europe is 86.5 in California. I believe that 91 is the minimum octane for California premium gas, so that is all we get. Chevron cannot sell it for more if it was 93. California also has additional restrictions on aromatics in the fuel that other states don't consider.

red308

The label on the gas tank cap reads as follows:

RON 98 Minimum
ROZ (93 Minimum)

It is a very confusing label given the way it is layed out on the sticker which I cannot exactly duplicate in this post.

I assume that the 98 number uses the Euro RON designation. I have to assume that the 93 number refers to the average on RON and MON as mentioned in a previous post.

In any case, there is certainly no mention of 91 Octane which is what is normally available. However, the owners manual ONLY refers to 91 Octane and never even mentions the numbers seen on the gas cap.

Ha. I suspect that MBUSA wrote the manual but the gas cap sticker was placed on the car at the factory in Germany.