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Bad Fuel?

2948 Views 6 Replies 3 Participants Last post by  BRN9121
Hi guys

I just picked up my car a few days ago and immediately noticed a light rough idle. I took her in today and they checked her up fully, no faults.

The service advisor tells me it's due to bad fuel and added an additive, asked me to drive her a little more and this should go away.

This isn't my first performance sedan, so I know something is not normal here. The car has 40 miles on it since driving her out of the showroom.

My E60 M5 and 997 PDK didn't have this issue. I know the 997 was DFI and my E60 was not. But this is the first time I see this on a brand spanking new car.

Any thoughts?
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The additive is probably Mercedes Keropur. It is made by another company and re-badged by Mercedes. Just google "Mercedes keropur additive" and you'll get a lot of info.

I use it with every tank on my G55 & C63 Black Series. Even though my cars are supposed to be GCC standard, the engines, fuel & exhaust are still somewhat Euro4/5 standard AFAIK. Some other car manufacturers do tune (or de-tune) their performance engines to our bad fuel but mercedes amongst others aren't doing that for environmental reasons.

The fuel we have in the GCC does not live up to Euro standard, I am sure about Kuwait at least. In Kuwait, we do have Euro 4 Gasoline but it is only available in 3 stations. I use it sometimes when I don't have a can of Keropur handy but it's 4 times more expensive than the ultra premium and the location of the stations are not very convenient.

I doubt the Mumtaz fuel in Bahrain lives up to Euro 4 standard. You might want to do a little more research before deciding what is the best course of action for you. Other Mercedes cars in my house hold and with some of my friends have had their fuel pump and even valves clogged because they don't use any fuel additive. This will be less apparent to drivers who drive a bit aggressively and tend to reach the higher rev levels of their engine frequently.

My G55 is a 2009 and the fuel pump is fine so far. My friend who has a 2010 G55 replaced his fuel pump during the first 6 months because he did not use any fuel additive and drives like a grand mother.

I hope this helps and keep us updated :)
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You are most welcome :)

I noticed you said that you use 97 RON and started wondering what are the RON ratings for the Jayyed and Mumtaz fuel in Bahrain? I am thinking about driving to Bahrain in the c63 to take it around the track. I was planing to use mumtaz fuel with the keropur additive. Is there a third kind of fuel in Bahrain's stations that I don't know about?
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