Trans-X do you recommend or not?
 

I have a 85 300D, 200K miles, and I am doing all of the major tune items. I want to change my transmission fluid tomorrow and I have heard use trans-x and I have heard its junk. Has anyone had any good or bad experiences with it? Will it effect my seals, or will it help clean it out? More important will it replace some fluid, I dont know how big the bottle is.

Don't use it unless your transmission is already conked out and you need something to get a few hundred more miles out of it. Just do a normal transmission fluid and filter change every 15-30k mi and be done.

Trans-x swells seals to reduce leaking. Obviously that isn't good for the transmission but, like H said, its good if you want to get a few more miles out of a worthless clunker.

Done use redneck product for the benz!!! Do it properly and skip all of the "TRANSMISSION HELPING FLUIDS" you save both money and time...

My tranny wrench says that, although stuff like that will sometimes fix a leak by swelling seals, it also can attack the glue that attaches the friction materials to the metal disks in the clutch packs. He recommends against it.

I just change my fluid and filter once a year with a good quality fluid like Valvoline Dexron VI Synthetic....it runs great with it.

Generally those "fixit" fluids cause many more problems than they solve.

I think it can be helpful in the following circumstance:

When you're going to change the fluids thoroughly, add a can the day before. It CAN help reduce sludge and gum buildup on the inside of a transmission. Whether or not this is a good thing for an old transmission is open to interpretation. But if you've got one on its last legs, or you don't know the last time the fluids have been changed, I say go for it.

Leaving a can in there... I don't want that stuff acting long term on the seals.

Running a good synthetic fluid on a good cycle will clean out more than a quick shot of Trans-X.....as has been mentioned it can harm the glues in the friction materials....not a good thing. I'd not use it.