foreyes

my 97 E420 has 209,000 miles now and has been very reliable. I've done all maintenance and services except for one thing, transmission fluid and filter change. The transmission shifts perfectly, but I'm starting to wonder if a service is due. I was once told that an older transmission can be damaged by a fluid change, as the higher viscosity of the new fluid can cause older, weak seals and gaskets to leak. The owner's manual states that the transmission fluid is "lifetime"...Any thoughts on a fluid/filter change at this point? The transmission has never been serviced. Thanks for your input

tirona

this is a hard question. i would definitely NOT flush it, but probably would change the fluid/filter/pan gasket. you can drain almost all of the old fluid since you have a drain plug on the torque converter, and when you are draining the old fluid out, it will take a good 2-3 hours for most of it to drain, some people even let it drain all night. your fluid will probably be really dark.

mistertonyn

If you made it to those mileage without ever changing the fluid then that is awesome. Are you the original owner?
My local dealership is saying that it is recommended at around 39K now. You are correct..the manual does say lifetime fluid. They should make up their mind. I have 75K on my 99 E320 and I am going to have it done soon.

Musikmann

I agree with the others and especially with Tirona that you should not flush it. I'm also astounded that you are still running with the original fluid. I would advise sending a sample of the old fluid to Blackstone Labs (or any competant lab of your choice) to see what the results are. Blackstone will send you a free sample vial and it should only cost you $20 + shipping.

foreyes

Thanks for the opinions, fluid drain and new pan filter and gasket then, without a flush. Good point about having a fluid analysis done, it would be interesting just to gauge the internal wear at this point. I am also amazed that there is zero engine oil consumption, it gets Mobile 1 and filter every 7,500 miles, and the oil level never varies by even a tenth of a mm on the stick. I am not the orginal owner, but am responsible for 100,000 of the car's 209k. This car amazes me both mechanically and cosmetically, the black leather interior still looks fresh, no creases or scuffs, the original paint still shines ( detailed obsessively with Zymol and Meguiars ), my neighbor's 2005 E500 shows more wear and abuse than my 97. I enjoy my 04 BMW 545i, but something tells me that it won't age as well or look and perform as well as the E420 when its 11 years old. The W210s truly have impressive build quality. Rear window regulators excepted.

Semikolon

IF you change your ATF now, your transmission may break. This is because the old fluid has no ability, whatsoever (if it's over 200k miles old), to loosen and transport dirt away from the gearbox into the filter and pan. But the new fluid will loosen all the old dirt, take it through the hydraulic mechanisms and into the filter, which eventually will get filled up and all the dirt will have to be left elsewhere. This will cause a breakdown.

If you plan to do this, it should be done at least twice in a very short time (both oil AND filter) or flush it.

I would go for the flush....

tirona

while i think semikolon's idea to change fluid/filter twice in a very short time interval is a great idea and makes a lot of sense, i don't agree with the flushing part.

Semikolon

why not flush?

tirona

because when doing the tranny flush all you are doing is swirl around the fluid with all the junk that is in the bottom of the pan and introducing it all over the place. also when doing the flush usually they don't even change the filter, so you are pushing fluid against the old dirty filter getting the particles caught out.

masoma741

What is the capacity of the automatic transmission flud for w210?

masoma741

How many liters of ATF needed for full replacement?

Semikolon

oh, ok, I was thinking of a proper flush, like the automatic transmission guys I know do. they drain and flush the whole system with a machine to get out all the dirt and old oil...

Semikolon

this depends....

If you drain just the pan and gearbox you will get out about 3-4 liters. If you also drain the converter you will get out additional 3-4 liters. It also depends on how long you drain. You have to let it drain for some hours to get out as much as possible.

If you are doing this yourself without a measuring dipstick you must measure how much you drain and fill the same amount (+ loss in paper, filter and other - about 1dl or so). Then I highly recommend visiting a shop with a measure dipstick to measure the fluid level.

Semikolon

also guys, remember, fluid after Mercedes specs for your 722.5/6 ONLY!! DO NOT us Dexron, Mercon or other fluids

Musikmann

I don't think they were using pan magnets in 1997 and the jury is still out on whether they are necessary. I personally think they are a good idea. Maybe your drain plug is magnetized (mine is not) but that has been a matter of debate as well. Good Luck!

mistertonyn

replacing filter and gasket is the best route. Total oil capacity should be around 9.3 liters. I am wondering if it would also be good time to have that O-ring on the TCU plug replaced also. I have been reading that sometimes the oil seep out and can damage the TCU and that is around $1600 to replace.

tirona

that is a good way, but would be too expensive, and most of the places i know here in usa don't go that route.
also changing the leaking plug connector that mistertonyn is talking about would be a very good idea, especially for us with the early 722.6 trannies. http://www.benzworld.org/forums/w210...ml#post2809739 (you might need to register at bw in order to see the pics)

Semikolon

yeah changing the plug is a very good idea. it probably leaks after that mileage and with a leaking plug you may get faulty and weird shifting. It costs about nothing...

Changed it on my 722.699 the other day. The pan was covered with oil from a leak in the contact