[Siddo90]

Hi guys,
I recently got a bmw and filled the tank fully with a 98 Ron fuel. And started noticing black sticky soot in the exhaust and it always used to look wet-ish. After the tank got to reserve, I filled the car this time around with 91 Ron fuel and to my surprise, the exhaust looked normal and there was no wet soot in the exhaust. The car in question is a bmw 320i 2007 model.

Has anyone else noticed this? I have attached an image of the soot too

[Socket]

Car should run on 98 no problems. Wet soot is because water vapor is combining with the carbon in the exhaust.... if you are not losing coolant then it could be the car is running rich on 98. Have it looked at and tuned by a mechanic and it should be fine

[Trev88]

Always run 98 mate

[david in germany]

You should always run the minimum octane the manufacture recommends not higher than they reccomended. This has been discussed so many times..
Tuned cars are the exception. Run the octane the car is tuned for.

Using higher octane than reccomended in non tuned cars is a waste, plain and simple.

[Desertraptor]

i found a motoring australia article recently that states unless you have a high performance vehicle that runs a turbo or supercharger you will get very little benefit from anything above 91RON. the manual will tell you what minimum RON. Yes it'll run of 95/98 but you will not see any more power.
the difference between RON rating is to do with compression. Higher compression engines require 95-98. Otherwise you are just putting unnecessary money into the tank for little return.
i posted a link to the article here somewhere.

[juld0zer]

Aussie journos are also probably sponsored to promote the use of E10

98 contains more cleaning additives. I personally run 98 but I've had cars in the past that had poor cold starting on 98. The official word from the dealer was to use 95 in winter.

Also check your spark plugs and coils, air filter. I see heaps of N46 have very clean tailpipes (surprisingly)

[Trev88]

Sure you're not driving a diesel mate? Kidding. But you've got more soot than my 320d.

[Siddo90]

Originally Posted by Trev88

Sure you're not driving a diesel mate? Kidding. But you've got more soot than my 320d.

Hey bud.. I know! That's a lot of soot
But after switching to 91 Ron, the exhaust looks much better. No black soot at all. Looks like a normal petrol exhaust pipe now..

[Desertraptor]

Originally Posted by juld0zer

Aussie journos are also probably sponsored to promote the use of E10

98 contains more cleaning additives. I personally run 98 but I've had cars in the past that had poor cold starting on 98. The official word from the dealer was to use 95 in winter.

Also check your spark plugs and coils, air filter. I see heaps of N46 have very clean tailpipes (surprisingly)

wont matter if th egov get it's way and ban 91RON. Will the cost of 95/98 come down accordingly.

[Desertraptor]

Originally Posted by Desertraptor

i found a motoring australia article recently that states unless you have a high performance vehicle that runs a turbo or supercharger you will get very little benefit from anything above 91RON. the manual will tell you what minimum RON. Yes it'll run of 95/98 but you will not see any more power.
the difference between RON rating is to do with compression. Higher compression engines require 95-98. Otherwise you are just putting unnecessary money into the tank for little return.
i posted a link to the article here somewhere.

Of course the down side to 91 is it is a dirtier fuel and has more sulphur content compared to 95/98. Strange that after I try 91 I start getting stuttering at takeoff.

[bradsm87]

Originally Posted by david in germany

You should always run the minimum octane the manufacture recommends not higher than they reccomended. This has been discussed so many times..
Tuned cars are the exception. Run the octane the car is tuned for.

Using higher octane than reccomended in non tuned cars is a waste, plain and simple.

I disagree. I always go one step above the recommended RON. I get audible knock in the work Hyundai i20s, Combos and the Holden Rodeo when running them on 91. They all have no audible knock whatsoever on 95 and get better economy. Engines age. They get carbon build-up etc.

Originally Posted by juld0zer

Aussie journos are also probably sponsored to promote the use of E10

E10 is an excellent fuel that gets a very bad wrap due to it cleaning the deposited crap out of people's fuel tanks and prematurely clogging their fuel filter, sometimes to the point of the car breaking down. Then they spread the word "Oh that E10 is rubbish. Made my car break down. Never again." Then it just spreads from there. Most of them don't realise that after changing the fuel filter, it would have run flawlessly from then onwards.

[Mayuri Krab]

91 rons have 3x more maximum allowed sulphur content than 95/98 (150ppm vs 50ppm), most euro cars aren't designed to handle that high of sulphur vs something like a local commodore imo.

I thought almost all "newish" euro car recommand 95 with 91 only to be used in a emergency.

[Desertraptor]

To my knowledge it wont hurt running on 98.
Have just run a tank or so of RON91 in my 325i and running was less than ideal. Put Shell v power 98 in and it came good again.

Coincidence?