"Ray Block" <bpracing@worldnet.att.net> wrote:
> Before anyone gets in a panic over this TSB Bernd so kindly provided, those
> of us with older vehicles that came from the factory with something other
> than ATF+4 should note that while the TSB says ATF+4 is backward compatible
> and can be used to top off vehicles that used ATF+3, ATF+2, or ATF+, nowhere
> does it say one *must* use ATF+4 (unless originally so equipped). It also
> does not say "OMG, we've been putting the wrong crap in our transmissions
> all these years and you'd better get it all out of there now or your tranny
> will self destruct."
Indeed. I don't recall what year the changeover happened, but if
your factory fill was ATF+4 then you should definitely be using ATF+4,
however, as Ray said if its been ATF+3 all along, you can keep using
ATF+3. I'm certainly no expert on the subject, but as I understand
it, functionally (as far as the friction properties and such go),
ATF+4 is actually identical to ATF+3. It was purposly designed this
way because it had to be made backwards compatible with transmissions
designed for ATF+3. So, there is no performance difference to be had
from switching to ATF+4. The main benefit of ATF+4 is the longevity.
It will last longer so you might be able to stretch out those trans
fluid change intervals. (IIRC, that was the main reason Chrysler
developed ATF+4, to give them a "lifetime fill" tranny fluid.)
Note that although ATF+4 is claimed to be backwards compatible with
the earlier ATF+3, +2, etc. it is known that it will attack certain
seals in earlier transmissions. (The trans will still work, but it
will leak.) Unfortunately I don't know what type of material those
seals are or what transmissions they might be found in, or how far
back we are talking, but this is something to be aware of. If you're
using ATF+3 now, I don't see any real reason to switch to ATF+4 unless
you're planning to take an around the world trip and/or never change
your tranny fluid again, especially when you consider the price
increase. (I believe ATF+4 is fully synthetic so that probably
accounts for most of the price difference.)
Regarding switching to ATF+4 in order to extend your fluid change
intervals, this sort of thinking always makes me a bit nervous, like a
synthetic oil giving you 10,000 mile oil changes. If your engine is
*designed* for 10,000 mile oil changes, maybe, but every engine is
different and the oil will pick up contamination from blowby, the
outside atmosphere, etc. No oil is going to be able to do anything
about foreign debris floating around in it. I think that's the main
purpose of a fluid change, not so much to replace a "used up" fluid,
as to flush out the crud that has been picked up.
If any of the above is incorrect, please feel free to correct me or
fill in the blanks, but that is the lowdown on ATF+4, as I understand
it.
--
-Jon-
.- Jon Steiger -- jon@dakota-truck.net or jon@jonsteiger.com -.
| '96 Kolb Firefly, '96 Suzuki Intruder, Miscellaneous Mopars |
`-------------------------------- http://www.jonsteiger.com --'
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