My 302 kmile 1992 300D has original 722.4 transmission.

Which ATF is better for that transmission, new Mobil 1 or Dexron VI (Pennzoil, etc.)?

The newly formulated Mobil 1 is recommended (by Mobil) for Mercedes-Benz 236.6, according to Mobil web page.

Dexron VI (six) has third party approval. In case of Pennzoil Dexron VI, it is not synthetic, and thus would be more old seal friendly.

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1992 300D 2.5 turbo diesel. 319 k miles.
124.128 chassis, 602.962 engine, 722.418 tranny.

Dexron is for Gm cars. I can send you document that lists approved ATFS for your tranny. The difference between the many types of ATF is the additives added and forumuled for specific trannys. While one atf maybe good for some trannys it may be bad for some.

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1986 300SDL, 211K,Dealership serviced its whole life
1991 190E 2.6(120k)
1983 300D(300k)
1977 300D(211k)

For 722.4, MB recommends Dexron ATF, and several dealers I know use the $3.99/quart non-synthetic Dexron III. One dealer I know uses even cheaper "Autozone" brand Dexron III ATF. The "Factory Approved Service Products September 2003" booklet has a list of Dexron III fluids - most of them are non-synthetic -. The sheet that came with my car also lists Dexron II fluids under "236.6".

I would appreciate if you send a recent MB list.

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1992 300D 2.5 turbo diesel. 319 k miles.
124.128 chassis, 602.962 engine, 722.418 tranny.

I put the valvoline Dexron VI full synthetic in all our cars, and they love it, smooth shifts and great performance. Cheaper too, Mobil 1 is insanely expensive, and the new formulation is not good for the old trannys. I change my fluid/filter every year....

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-diesel is not just a fuel, its a way of life-
'15 GLK250 Bluetec 118k - mine - (OC-123,800)
'17 Metris(VITO!) - 37k - wifes (OC-41k)
'09 Sprinter 3500 Winnebago View - 62k (OC - 67k)
'13 ML350 Bluetec - 95k - dad's (OC-98k)
'01 SL500 - 103k(km) - dad's (OC-110,000km)
'16 E400 4matic Sedan - 148k - Brothers (OC-155k)

valveoline is on the approved list. valvoline atf type D

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1986 300SDL, 211K,Dealership serviced its whole life
1991 190E 2.6(120k)
1983 300D(300k)
1977 300D(211k)

Thanks for the file. It was also among the very helpful 722.4 transmission files you sent me recently.

As GM does not approve Dexron III anymore, many Dexron III products were discontinued or name-changed. I cannot buy Valvoline ATF Type D any more. Some local stores have Valvoline DEX/MERC ATF instead, and I do not know whether the Valvoline product with the new name is also MB approved one.

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1992 300D 2.5 turbo diesel. 319 k miles.
124.128 chassis, 602.962 engine, 722.418 tranny.

Yes, Dexron III was specified for pre-2005 GM cars, and the newer THINNER Dexron VI is specified for the newer GM cars. Viscosity index on the VI is about 10% thinner than the older III.
Does this make any difference on the older MB cars like my '91, that specifiy in the owners manual that you can use Dexron III - I don't know, but I will stay with the III as long as I can find it.
I found Pennzoil Dexron III at Pep Boys last week.

DG

According to a web page whose credibility I do not know, Dexron III starts with higher viscosity, but the spec allows the viscosity to drop to a certain level as the fluid is used. Dexron VI has initially lower viscosity than Dexron III and its viscosity will drop to a certain level too, but not lower than the level allowed in Dexron III spec. That is why Dexron VI can be used in transmissions requiring Dexron III.

Since GM does not approve Dexron III anymore, a Dexron III fluid available now has only the oil manufacturer's claim that they (the oil manufacturer, not the car manufacturer or the transmission manufacturer) recommend their fluid for Dexron III applications. In contrast, Dexron VI fluids on the market passed GM's test.

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1992 300D 2.5 turbo diesel. 319 k miles.
124.128 chassis, 602.962 engine, 722.418 tranny.

Unfortunately Mobil has removed itself from the compatibility race with it's "NEW" additive package.

The Valvoline Synthetic product is intriguing,I'll have to investigate.

The following Two Products will provide superior service (At a "superior"price)


Redline Synthetic Oil Company

OR


Royal Purple ATF:

Mercedes Benz 236.x > Max ATF

Unsure about which product is right for your application? Contact Royal Purple’s Technical Support department toll-free at 888-382-6300 or Email Technical Support.

Attached Thumbnails

   

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'84 300SD sold
124.128

The new Mobil 1 ATF web page still states "Compatible with mineral ATF fluids and all common seal materials".
http://www.mobil.com/USA-English/Lubes/PDS/NAUSENPVLMOMobil_1_Synthetic_ATF.asp


Mobil 1 ATF and Valvoline Dexron VI are both synthetic. Why is Valvoline more old seal friendly? Is it because Mobil uses PAO while Valvoline uses group III base stock?

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1992 300D 2.5 turbo diesel. 319 k miles.
124.128 chassis, 602.962 engine, 722.418 tranny.

A lot of "seal friendly" comes from additives. True synthetic oils don't swell rubber as much as traditional dino oils do, and less swell can spell a leak to old seals. The solution is in the additives, synthetic oils have additives to swell the seals as much as dino oil, but it can vary.

There is no danger in a fluid with less swell, it will leak and require the old type oil again to properly seal. If the oil has MORE swell, it can cause the seal to wear and you can't go back.

__________________

Gone to the dark side

- Jeff

KTLIMQ, that article about the Dexron III vs VI seems to make sense.
Do ATF fluids lose viscosity during use? I understood that multi-weight traditional motor oils became thicker with use, due to the loss of the lighter, more volatile molecules. That is supposed to be one of the big advantages of synthetic motor oil. But, I never thought about ATF changing viscosities one way or the other.

As my old '91 tranny aged, I sitched to the Valvoline Max Life ATF, supposedly designed for older cars, it is supposed to have additional seal conditioners and a bit more viscosity - yada, yada. So far, so good, I have had zero leaks - but I did wear out the reverse clutch plates. Probably not related.

DG

"additional seal conditioners" in most transmission stop-leak formulas and "high mileage" ATFs are naptha, benzene, "petroleum distillates", acetone, ... any solvent that softens rubber. Not good for the long-term, but can extend the life of a failing transmission's seals.

I've heard of everything from brake fluid to acetone added to a transmission to make it shift when (internal) seals are leaking too much to have adequate control pressure at idle.

Best to just run good ATF if your only leak is external IMO, cardboard is cheap.

__________________

Gone to the dark side

- Jeff