My wife's '96 C280 has been afflicted with the erratic fuel gage syndrome. It seems to happen with several different brands of gasoline, although I am now placing her on a strict diet of Exxon Premium for the next few tanks, just to see if it clears up. If it is not caused by the fuel, how do I go about replacing the sending units? (I think that there are two?) Does anyone that has done this in the past have advice to offer? Thanks.

#1 fuel senders on that vehicle are not an easy job without a lift.
#2 draining the fuel could be very messy and frustrating without the MB adapter
#3 the lock rings that hold the senders in need a special MB tool in order to remove.

Without diagnosis, the repair should be less than 2 hours. I'd advise taking it to a shop that will back up their work- it'll save you a lot of headache and should be a quick fix.