Transmission fluid change interval?

[Serndipity]

Thanks to the $100 coupon, just got my oil/filter changed at the local dealership. As I'm coming up on 75,000 miles, while there, I asked about their recommendation on changing the transmission fluid and serpentine belt. Supposedly my transmission fluid in the 2001 CLK320 is lifetime. However, I've read many forum postings that dispute this claim and I was told by the service adviser that MB has changed lifetime to 39,000 miles flush/change ($300). To date, other then frequent oil/filter/coolant changes, the only repair needed was replacement of a MAF. Do most of the work myself or sometimes use an independent. I would be interested in the groups wisdom regarding the suggested mileage for changing the transmission fluid and if a drain and replace would be OK (vs. flush and replace). BTW, their reply on the belt was 'it depends'. I'm thinking that even it it shows no cracks, unusual wear and tear, it would better to replace it now (vs. risk breakdown). Thanks in advance for comments.

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[gorgerider]

My indy mech says 30K is a safe number. I hadn't seen the 39K number before, but it certainly sounds resonable. Just be sure to drop the pan and change the filter when you do it (don't just allow them to hook up the flush machine and change fluid only or just drop the pan fluid only).

At my "local" dealership (100 miles away), they charge $22 a liter for fluid. I get Mehle (German) with the proper spec for about $8.50/liter at a local parts house. Another thread on this forum says a Valvoline product works just fine for less than $4/qt.

I don't believe your 2001 CLK 320 has a drain plug for the torque converter, so you will need 13-14 liters of fluid to flush all available fluid. Take a look at the procedure on Post #144 in the "How To" thread. If you don't want to get oily, print the procedure and take it to your local indy shop or good oil change operation. You will also need to bring them a transmission fluid "dipstick" in order to make sure the fluid ends up at the right level. These are considered a "special MB tool" and the dealership gets about $45 for them. I see them on eBay for about half of that and a number of internet parts houses carry them. In any case, good thing to have hanging on the garage wall. Also, make sure you get a good quality filter/gasket kit (not a part on which to skimp).

There are no trajectory calculations or hydrazine involved (hence, this is not rocket science).

On the belt, just make sure (translation: "prepare for") having to replace the belt tensioner while you're at it. Also, take a good long look at the water pump while you're in there. I don't know about frequency or the procedure, but these guys will be able to help you better. Good luck.