I have a 93 400e. I have a wonderful book that was written by people that are especially knowledgable about this car. They know everything about this car. They designed this car and have build thousands of them.
That book is called an "owner's manual".
In it, these experts recommend changing the oil and filter each 7000 miles under normal driving conditions, and changing the oil each 3750 miles and the filter each 7000 miles under severe driving conditions. Now, I know that the gents at Jiffy Lube want you to change your oil each 3000 miles. You tell me whose advice you are going to take - Mercedes engineers or your corner lubrication vendor?
Just buy a good brand of filter (you know, MB) and use good oil (I personally love Mobil 1, just because it does the best in all the tests I have read) and change your oil whenever you feel like it (3000, 3500, 4000, 7000 miles) as long as you stay within manufacturer reccomendations and you will be just fine.
Trust me, just change the oil and filter on schedule, and I guarentee that the rest of the car will wear out before the bottom end of the engine does.