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Re: [T3] Synthetic ATF


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Jim Adney wrote:
> On 16 Sep 2004 at 14:44, Steven Cooper wrote:
>
>
>>The reason I was considering synthetic ATF was that I assumed it
offered the
>>same benefits as synthetic oil.  Slower thermal degradation and lower
>>temperatures.  As oil is changed every 3000miles or less in an aircooled
>>engine, synthetic oil is not worth the money.  However as ATF is left in
>>much longer, I thought it may be worth it.  I have not even looked at the
>>claims made by manufacturers yet.
>
>
> The temps seen by ATF are a lot less than in an engine, and AFAIK
there is
> little or no breakdown of ATF in normal use over any time period. I
suspect
> that the only reason for changing it in our cars is to get rid of wear
> particles which the strainer doesn't remove.
>
> If the synthetic ATF could provide the same benefits while having lower
> viscosity losses that would be a plus, but those losses are pretty much a
> function of viscosity and if we reduce the viscosity then the torque
converter
> doesn't work as well. So I think there's not much benefit to be had.
>

It's not uncommon for an automatic transmission to heat the fluid to
200+ degrees.  Especially under loaded conditions.   Remember, when it's
shifting gears, it basically eases into one gear while releasing the
clutch on another gear.   This generates friction and with a heavier
load, it generates more friction.   The trans essentially slips into the
next gear.  Synthetics have long been known to withstand higher
temperatures without breaking down.   If it were _MY_ car I'd have the
better stuff in it, especially if I were going to be subjecting it to
any loads.   Some sort of trans cooler helps also, the cooler you can
keep the trans fluid, the longer the trans will last.  Automatics
usually overheat the fluid, glaze the soft parts (clutch material on the
bands) and start slipping.  Most the failures are soft parts.   Unless
of course it is behind one of my engines. :)

- --
Mark Wolfe           Lakeside, ca            http://www.wolfenet.org
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