I hear all kinds of people talk about all sorts of supplements, some may works and some, you are making someone else rich on their lies.

Myself, being a ex-OTR truck driver, I know what works and what doesn't.
Going to a truck parts place, and you find a lot of truckers buying one ceratin brand and then you find out Mercedes endorses it, you begin to realize that 90% of the truckers can't all be wrong!
Trucks bring us our bills and our mail and the fuel we all burn in our cars.

I use Diesel Kleen (silver container) made by Power Service. I was running Diesel Supplement (white container).
Now as all of you 240D owners, we all know how much a small improvements make on a 67 horsepower rated engine can make!
An Ounce seems like a lot!
With Diesel Kleen, I swear it added 5-10 horse power! I can leave it in 3rd gear and go around a street corner and actually step on the throttle and feel a gain in speed! Before DK, it would die flat on its' face, had to Always drop to 2nd gear.

But, I will warn you all trying this. If you mix to the max cetane of 6 points and you use Amoco Premium - don't be surprised if you sound like a Power Service employee to your friends!

One other problem is, you had better find a good place that stocks up on it, cause once you feel the difference, you won't ever want to run out of it!

I noticed a difference after about 150 to 200 miles, every mile thereafter, it seems to run better and better. As for the fuel mileage, it has increased slightly from about 2.5 to 4 mpg's. And it has been consistant too.