What's the most appropriate ATF?

[CalicoJack]

I have a 1983 300D, and I'll be changing its transmission fluid pretty soon. What with Dexron II not being an option anymore, what specification would you guys recommend as having the best backwards compatibility and being most appropriate for a thirty-year-old transmission? I've been told Mobil 1, but other people said no, they changed their formula, you shouldn't use them now. The guy at Autozone said the new Dexron VI is completely compatible, so just use it, but it was my understanding it has different viscosity characteristics. Am I wrong?

I suspect asking about brands could start a war, so I'm not even gonna go there.

Thanks for any help you can give me!

[sixto]

I heard Dex VI isn't good for these trannies but I had no problems over 20-30K miles. That was after Mobil 1 for 50-60K miles with no problems. Presently running B&M Trick Shift synthetic. Sticky stuff. I have to back off the modulator. Redline D4 is about the only ATF that still claims Dex II (IIE?) compatibility. Any basic ATF should be fine.

Sixto
87 300D

[NoSparkNeeded]

I've been running Dex 6 for 3 years in my TD and wife's SD with no problems. Shifts are nice, maybe a little "crisper" than Dex 2 that was in it before, but the effect is subtle. I'm sticking with that for the time being, unless I read something really negative.

[CalicoJack]

My understanding of Dexron VI is that it starts off thinner but stays thicker over time than Dexron II or III--the specification allows for much less variance. That doesn't really bother me as much as whether or not the chemistry is compatible with seals or parts used in the Mercedes transmissions. But I would think that over three years or so, if it was going to degrade anything, it would have by now. So since everyone keeps saying that Dexron VI is, in and of itself, a much superior fluid to earlier Dexrons, I'll probably just use that unless someone tells me differently.

If you transmissions suddenly blow up, I'd be obliged if you came here and posted a warning so I know to get that junk out of there as soon as possible, though!

[cooljjay]

My thought and what I have read, valvoline dex/merc is good.....running that now in mine....

[Skippy]

When I had an autotragic in my 300, I used Dexron III. Aside from a rather bad front seal leak, it was still working perfectly when it came out for the manual conversion at 310,000 miles.

[CalicoJack]

Well, heck, there seems to be plenty of people running Dexron III and VI with no problems. I'm glad to hear all this, I'll give VI a try and let 'er rip. Thanks to everyone who put their two cents in!

[rscurtis]

I use Amsoil Universal ATF in my signature car, it seems to work fine.

[pawoSD]

Valvoline Dexron VI synthetic in two 300SD's, two 420SEL's, and a 190d (with 1993 190e trans) here, no issues in a combined mileage of probably over 175,000 on this trans fluid by now.

Also ran it for 40k in my bro's 300D, it died from rust, transmission still worked.

[BillGrissom]

This gets asked a lot. I recall there is no firm factory-approved answer. I recall putting Dexron VI in one of my 300D's last time. I wouldn't be averse to using ATF+4 either, since I understand it is the best "standard" fluid (i.e. not after-market), plus I use it in all my Chryslers both new and old. Type F might also be good, since it had more friction (less slipping & wear of clutch plates). It was used in old Fords and I used to use it in my old Mopars. In general, you want fast, firm shifts to minimize wear. There might be an issue with some clutch plate linings failing in some fluids, so read up, but might be mostly hearsay.

[Skippy]

I might have tried Type F in mine if I was needing a shift quality improvement, but I already had it where it would sometimes chirp the tires on the 1-2 shift, so I didn't need to go there.