Synthetic okay for older transmissions?

[Kestas]

I was just reading a post on one of the Mercedes forums talking about using (or not using) synthetic fluid in a transmission from the 90s that specified DexII. He said the transmissions were not engineered with synthetic in mind, and synthetic is too slippery for such transmissions, and added that the clutches will slip and lead to early failure.

Isn't Dexron a performance requirement, and not necessarily a fluid requirement (i.e., regular vs. synthetic)? If the abovementioned was true, wouldn't it hold true for all older transmissions that specifed Dexron? I think this guy is blowing smoke.

 

[The_Jeff]

I agree with you. This is a horrible analogy but imagine if you're outfitting an army to go do stuff. Now imagine if all your soldiers were 5'11" and wore 34/34 pants. They could do everything with all your gear, and just be more... uniform.

A synthetic origin just distills the "dud" molecules who would be the oddly sized soldiers in this analogy.

Now I know I owe the board readers a better explanation but cannot at present conjure one.

 

[Bgallagher]

the synthetic versus conventional sounds bunk to me. I would use maxlife. Dex speced and synthetic. Many people will attest that it works great

 

[UNC017]

People confuse "synthetic" with "highly friction modified synthetic." I wouldn't use ATF+4 in that application (even though its nominally backward compatible all the way to type "A") because of the friction modifiers. But a synthetic Dexron fluid? Shouldn't be a problem.

 

[hounddog]

I used Amsoil Universal AFT in 80s model vehicles.

 

[tig1]

I used Mobil 1 ATF in the early 90s(still do today) in Fords with no negitive issues.

 

[JHZR2]

Im not sure if the slippery part stands, but the compatability of Dex VI with elastomers and other parts in Dex II or "older" transmissions seems to be an issue. As I understand it, this was brought about under the Allison transmissions, and IIRC, transynd or whatever their fluid is, remains partially because of elastomer compatability.

Ive not put DEX VI into my 80's MB ATs for this reason...

 

[Artem]

Originally Posted By: tig1
I used Mobil 1 ATF in the early 90s(still do today) in Fords with no negitive issues.


I'm also using Mobil 1 synthetic ATF transmission fluid in my 98 Camry V6 and have been for a good 6 years and over 150,000 miles of use without any issues. Transmission shifts as smooth today as it did when the car was new (i installed M1 into the transmission at around 60k miles. The car currently has 225,000 miles.

The whole synthetic is bad for older cars is pure horse droppings! If you use THE PROPER spec'd oil and it just so happens to be synthetic, you're just benefiting the car. Nothing negative will happen.

Things "might" go wrong if you use a synthetic transmission fluid that's a "one size fits all" type of juice.

If your car requires Dex III for example, use a good synthetic that says it's designed for dex III requirements.

 

[MolaKule]

Quote:
synthetic is too slippery for such transmissions, and added that the clutches will slip and lead to early failure.



Synthetic base oil simply extends the oxidative life of the formulated fluid. It's the friction modifiers in the PI (performance) additive package that primarily determines the friction modification.

I don't know where this "slipperyness" myth came from, except Reline does have this silly statement in their Manual Transmission fluid section that states, "Since most GL-5 gear oils for differentials are too slippery for manual transmissions, Red Line offers these products that ensure proper shifting while providing ultimate wear protection"

Slipperyness is a not a proper tribological term anyway.

 

[jsnyder49090]

Many of the high performance fluids B&M TCI etc say not to use their fluids in cars newer than 1999.

 

[Donald]

Use Amsoil ATF if its speced for your transmission. You will not be disappointed.

 

[Pablo]

Originally Posted By: MolaKule
Quote:
synthetic is too slippery for such transmissions, and added that the clutches will slip and lead to early failure.



Synthetic base oil simply extends the oxidative life of the formulated fluid. It's the friction modifiers in the PI (performance) additive package that primarily determines the friction modification.

I don't know where this "slipperyness" myth came from, except Reline does have this silly statement in their Manual Transmission fluid section that states, "Since most GL-5 gear oils for differentials are too slippery for manual transmissions, Red Line offers these products that ensure proper shifting while providing ultimate wear protection"

Slipperyness is a not a proper tribological term anyway.



Best statement on BITOG in awhile.

Shoot. I guess we can go home now.

I used Amsoil ATF in a 1985 AW71 in Volvo. Does that count?

 

[mechtech2]

If the final spec is Type F, Dex VI, or whatever, the friction characteristics are the same whether conventional or synthetic.

 

[Ken2]

Originally Posted By: JHZR2
Im not sure if the slippery part stands, but the compatability of Dex VI with elastomers and other parts in Dex II or "older" transmissions seems to be an issue. As I understand it, this was brought about under the Allison transmissions, and IIRC, transynd or whatever their fluid is, remains partially because of elastomer compatability.

Ive not put DEX VI into my 80's MB ATs for this reason...
That was only for certain models of Allison transmissions. They retain the GM Dexron-III spec, but now call it the Allison TES-389 spec. I do not know if the lighter viscosity Dex-VI fluid is suitable for your Benz.