[V8] AT powerflush?

[David Head]

First off, it allows the seals and components a slow introduction of new fluid for the
seals and components - extremely important in an old transmission. Secondly, at 5 bucks
for 4 quarts, I could change the fluid 18 times for the cost of the powerflush...
The powerflush will not do a 100% change. Some mixing always occurs.

Barry Bentley wrote:

> Mike,
>
> I am planning on doing this within the next week or so. I bought Red Line
> Synthetic ATF and am taking it to my local mechanic. He recently got the
> flushing machine. He's a cautious guy and he checked the manual that came
> with it and it said it was OK to do it on the V8 transmission. I've had the
> car since new (it's a 1992), and unless the dealer changed it and didn't
> indicate it on the 3yr/36,000 mile free-scheduled-maintenance repair orders
> (not likely) it hasn't ever been changed (the car now has 85,000 miles on
> it). I haven't had any particular trouble with my transmission, but it is
> overdue for a fluid change. I have seen some posts on using the flushing
> machines here in the past (search the archives for trans flush will probably
> turn them up) but they were inconclusive. I was hoping someone else would
> answer your question more definitively (particularly if it's a bad idea),
> but once I get it done I'll let you know how it turned out.
>
> I've seen lots of post suggesting the "drain pan and fill with 4 quarts 3
> times" method, but the chemical engineer in me does not like that solution.
> Supposing that there is a total of 10 quarts in the transmission, the first
> time you are draining 100% old ATF, leaving 6 quarts of old fluid. But then
> you add 4 quarts of new fluid, the new mixes with the old and the second
> time you're draining 40% new fluid along with 60% old fluid, leaving (6 -
> 2.4) = 3.6 quarts of old fluid in the 10 qts in the car after the second
> fill. So the third and final time you are draining 64% new fluid and 36% old
> fluid, leaving about 2.2 quarts of old fluid in there. My actual suspicion
> is that new fluid mixed with old takes on a lot of the bad qualities of the
> old fluid, but I don't know that for a fact or have any evidence that it is
> the case. For that matter, I don't know that a flushing machine does any
> better in terms of "pushing out" the old fluid in front of the new fluid, it
> might be that in reality it uses the same dilution technique as changing the
> fluid in the 3x4qt popular method. Furthermore, I don't doubt that the 3x4qt
> method is safer, but I've got it in my head that I'm going to try the power
> flush and there you have it.
>
> Barry Bentley (Ph.D. Chemical Engineering, Caltech 1985)
>
> '92 V8
> '01 S8
> '98 A6 (son's)
> other non-Audis.
>
> -----Original Message-----
> From: Mike Brown [mailto:mmlk23 at bellsouth.net]
> Sent: Wednesday, October 02, 2002 10:55 PM
> To: v8 at audifans.com
> Subject: [V8] AT powerflush?
>
> This is a multi-part message in MIME format.
> --
> [ Picked text/plain from multipart/alternative ]
> Hi Gents,
>             With 125000 on the OD and an uncertainty as to when the AT
> was last serviced, I was wondering if anyone has had an AT power flush
> performed on their V8.  I found a shop here that will do it for $89.00.
> I was told that the power flush will clean out the filter as well.  Any
> nay's or nods about this procedure?
>
> BTW.  Oddly enough, my car HAS the AT dipstick.
>
> Thank You in advance
>
> Mike Brown
> 87.5 Coupe GT
> 90 V8 Quattro
> --
>
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