C250 Turbo only.
Senior Member
Joined: Feb 2011
Posts: 465
Likes: 16
C204
There is a difference but not everyone can notice it. It is not like adding 50hp but there is a little effect. Btw, if you put a Brabus performance module, you will be required to refill with 98+ fuel only.
Super Moderator
Joined: Jun 2008
Posts: 19,942
Likes: 192
From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
Higher octane fuel allows one to run more advanced timing/higher CR.
Last edited by Glyn M Ruck; Dec 26, 2012 at 06:48 AM.
Super Moderator
Joined: Jun 2008
Posts: 19,942
Likes: 192
From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
Fuel in Europe is very good stuff. You probably don't drive in a fashion that encourages knock. e.g. WOT at low RPM. If you don't run 98 there will be occasions that the ECU is retarding timing but as I've said Benz runs conservative advance curves. In China where fuel is poor these engines knock frequently.
As the engine gets older you might find it is more inclined to need 98 due to combustion chamber fouling & hot spots.
As the engine gets older you might find it is more inclined to need 98 due to combustion chamber fouling & hot spots.
Trending Topics
MBWorld Fanatic!
Joined: Sep 2008
Posts: 1,331
Likes: 9
From: Delaware
2004 Mazda6, 1993 RX7
Glyn, just for clarity, the pump gas in europe (and China?) is based on the RON number, which is about 4 points higher than the US AKI rating (RON + MON)/2 .
My experience is that if you run a gas that is several octain points higher than the advance curve requires, then your perfomance can be degraded. The energy available from high and low octane gas is about the same, but you need to run the maximum advance each fuel requires to get that full energy rating.
.
My experience is that if you run a gas that is several octain points higher than the advance curve requires, then your perfomance can be degraded. The energy available from high and low octane gas is about the same, but you need to run the maximum advance each fuel requires to get that full energy rating.
.
MB World Stories
The Best of Mercedes & AMG
7 Craziest Things AMG Gas Ever Built
Verdad Gallardo
New Electric Mercedes-AMG GT 4-Door Coupe Unveiled: 10 Things You Need to Know
Verdad Gallardo
6 Mercedes Models That Did NOT Age Well (But Are Somehow Still Cool)
Verdad Gallardo
Manual Mercedes? 6 Times Sindelfingen Let Drivers Have All The Fun
Verdad Gallardo
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
Verdad Gallardo
8 Classic Boxy Mercedes Designs That Have Aged Like Fine Wine
Verdad Gallardo
Flawlessly Restored Mercedes 190E Evo II Heads to Auction
Verdad Gallardo
Electric Mercedes C-Class Unveiled: 11 Things You Need to Know
Verdad Gallardo
Mercedes EQS Gets A Major Update: Everything You Need to Know
Verdad Gallardo
Super Moderator
Joined: Jun 2008
Posts: 19,942
Likes: 192
From: Llandudno, Cape Town, South Africa
late 2009 CLK 350 Coupe Elegance, '65 Jaguar S Type wires
Yes ~ both are based on RON although in Europe there is usually slight octane giveaway whereas in China the fuel frequently does not meet the claims.
Regarding your other comment that can sometimes be correct depending on fuel blend. It's a matter of achieving complete combustion at the right time. With pump gas & moderate tune you won't really be able to measure any difference in my experience. Winter fuels in Europe have very little heavy end to them as well.
With 100 Octane racing fuel or 102 Aviation piston engine fuel the density is usually higher with more heavy end in the blend. Then it's desirable to have that slightly more advanced timing to complete the burn cycle. It's very fuel blend dependent rather than octane dependent as long as you have enough octane to prevent knock. In racing you are usually running as close to detonation as you can get away with. Of course in racing sometimes people overdo it with dire consequences. To be fair moreso with two stroke engines.
Regarding your other comment that can sometimes be correct depending on fuel blend. It's a matter of achieving complete combustion at the right time. With pump gas & moderate tune you won't really be able to measure any difference in my experience. Winter fuels in Europe have very little heavy end to them as well.
With 100 Octane racing fuel or 102 Aviation piston engine fuel the density is usually higher with more heavy end in the blend. Then it's desirable to have that slightly more advanced timing to complete the burn cycle. It's very fuel blend dependent rather than octane dependent as long as you have enough octane to prevent knock. In racing you are usually running as close to detonation as you can get away with. Of course in racing sometimes people overdo it with dire consequences. To be fair moreso with two stroke engines.
Last edited by Glyn M Ruck; Dec 28, 2012 at 11:53 AM.
