I still haven't heard anything telling me *why* new fluid can be a bad
thing.  What is the physical or chemical mechanism at work here??

Larry A.

On Mon, Jul 18, 2011 at 3:13 PM, Scott Daniel - Turbovans
<scottdaniel@turbovans.com> wrote:
> a compromise cheater method is to just change some of the ATF.
> use the right type ATF of course..
> I have a sucker tool I made with an old fuel pump .
> and I just pull maybe 2 qts of old ATF out of the dipstick tube..
> then top up with new fresh good ATF.
>
> If I do that on a properly working auto trans..
> and put in two qts of new Royal Purple synthetic ATF ..the trans 'goes'
> noticeably better.
>
> and for sure ..
> on any fluid system that is very shaky and old..
> especially brakes, clutch hydraulics and auto trans..
> if it's on the edge already............changing the fluid 'a lot' can
> totally blow out the whole system ...like push it over he edge to complete
> failure..
>
> Scott
>
>
> ----- Original Message -----
> From: "J Stewart" <fonman4277@COMCAST.NET>
> To: <vanagon@GERRY.VANAGON.COM>
> Sent: Monday, July 18, 2011 5:09 AM
> Subject: Re: Automatic transmission question
>
>
>> Larry,
>> I was told at the time it was due to mixing old/new trans fluid. It was
>> back before the power the power flushing like they do today, so only some
>> of the trans fluid was changed, basically what was in the pan. I have also
>> been told by a couple of mechanics that if you have a high mileage vehicle
>> and don't know if/when the trans fluid has been changed it is best to
>> leave it alone unless you are having problems. Jeff
>>
>>
>>
>> Jeff Stewart
>>
>>
>> ----- Original Message -----
>>
>>
>> That is very interesting. I hope that someone out there can explain
>> how and why this would happen.
>>
>> Larry A.
>>
>>
>> On Sun, Jul 17, 2011 at 10:16 AM, J Stewart <fonman4277@comcast.net>
>> wrote:
>>>
>>> Now, that brings up a question I have. I've now owned my '85 w/auto trans
>>> for just over a year. Even though the PO gave me a ton of maintenance
>>> records going back 10 years, nothing about the trans fluid ever being
>>> changed-tho it could have been done at a Jiffy Lube, who knows. It has
>>> been
>>> my (unpleasant) experience on two used vehicles where trans fluid status
>>> was
>>> unknown that changing the fluid caused total transmission failure with a
>>> few
>>> days. Since my fluid looks OK and the trans is shifting fine, I've
>>> decided
>>> to just leave it alone. Jeff
>>>
>>> Jeff Stewart
>>>
>>>
>>> ________________________________
>>>
>>> Jim,
>>> Change the fluid every two or three years. You don't get to drain
>>> it all because of the torque converter, but that's the best you can do
>>> without expensive flushing procedures. Check fluid warm, idling, with
>>> van level. Do not overfill. Frequently lubricate the place where the
>>> throttle cable from the front hooks to the lever on the side of the
>>> trans. It's a ball that snaps into a spring loaded socket, a real
>>> PITA if it rusts solid.
>>> Leaks that can be tracked down visually:
>>> Bottom pan gasket
>>> Filler/check tube joint to pan
>>> O-ring on the governor cover (up on the side of the differential,
>>> held on with a wire bail)
>>> Rusted thru governor cover
>>>
>>> Common and annoying leak: Seal behind the torque converter. This
>>> is the usual suspect if you seem to be getting oil spray on the left
>>> side of the engine compartment that may be coming out of the openings
>>> in the bell housing and the torque converter looks oily. To get to
>>> this seal you separate the engine and transmission. Don't let the
>>> torque converter fall off the front shaft prematurely. Then carefully
>>> pull the torque converter off the front shaft and you will see the
>>> seal that it fits into. What fun!
>>>
>>> Larry A.
>>>
>>>
>>>
>>>
>>> On Sat, Jul 16, 2011 at 7:36 PM, Jim Felder <jim.felder@gmail.com> wrote:
>>>>
>>>> I have a 91 Vanagon GL automatic that my daughter drives. I've done a
>>>> little
>>>> work on it over the last year or so and it is in pretty good, reliable
>>>> shape. The one thing that is giving me some trouble is the automatic
>>>> transmission. If you can help me with that, read on.
>>>>
>>>> I have driven Vanagons for 20 years or more, but I have never had an
>>>> automatic transmission. I have done about everything you can do to a
>>>> vanagon, almost, except mess with an automatic transmission and though
>>>> my
>>>> wife has had them on her non-vanagon cars, I have never had an automatic
>>>> Vanagon. I just recently learned how to check the fluid level in them. I
>>>> know virtually nothing about them. My daughter's car is leaking AT fluid
>>>> so
>>>> that it has to be topped up once a month or so.
>>>>
>>>> So I have two questions. One, what should I do, in general, to the
>>>> automatic
>>>> transmission just to keep it in good shape? What are the preventive
>>>> maintenance best practices? Two, what should I do specifically about the
>>>> loss of fluid; what is a "usual suspects" list of things to address?
>>>>
>>>> Thanks,
>>>>
>>>> Jim
>>>>
>>>
>>>
>