Auto Trans. bull#### - Toyota Nation Forum : Toyota Car and Truck Forums

patcal · 05-07-2009, 01:33 PM

Hey,

I was just told by a place I called that changing the auto tranny fluid & filter may do more harm then good. He said the flush would remove the varnish that could be sealing everything up. I have only heard this once before but I think it's bull. My car has 127K and sat for about a year before I bought it. It is shifting fine but want to keep it that way. Thoughts?

toyotaspeed90 · 05-07-2009, 02:00 PM

there actually is truth to that.... ATF is pretty corrosive as it has high detergents in it....

you may want to pull as much as you can out yourself, refill, run it for a while, and then pull the pan, drain, replace the filter, and then refill - if stuff gets knocked loose you don't want it to be in there long.

patcal · 05-07-2009, 08:58 PM

I thought he was just giving me a line. It only takes about 3 quarts plus 1.4 pints for the diff. Thanks.

Ghostyman · 05-07-2009, 09:11 PM

I'm a complete proponent of changing fluids but I've heard the same thing about auto transmissions from some people who I trust. Never owned one myself though, so I don't have any long-term experience with them.

ATF is definitely highly detergent. I use it for cleaning engine internals. In the engine, I don't worry about breaking chunks of sludge loose or whatnot because I know I'm going to change the oil soon. But with the tranny, you leave it in for a very long time. Toyotaspeed90 is right (as always; he is unto a god to us), I think the best bets are either to leave the fluid in until problems appear or change it twice in short succession.

*** Hey, look! This post is worthless, I just realized I parroted almost everything from the first reply. Oh well.

patcal · 05-08-2009, 07:44 AM

It is not worthless. It is always good to hear from more than one person. I am going to drain just the drain plug and fill it up and leave it maybe a week then do the whole thing. I will also do the diff then. Thanks.

ericdude · 05-09-2009, 12:44 AM

When I changed the filter on a high mileage transmission that hadn't seen a fluid change in
probably 60K miles, I was surprised--the filter, a fine screen-door type mesh, was basically
like new, with maybe 3 visible particles. The filthy part was the magnets in the pan; some
kind of goop was around them and I had to spend some time cleaning them.

I had a hell of time getting the pan to stay on properly when torquing the bolts to the
factory 43 in-lbs. The first gasket (that came with the filter) was a very flexible rubber
that came folded up into a wad and it started leaking in about a week with all the
bolts at full torque. I switched to a felpro stiff rubber gasket and that one was much
better. Every few weeks it starts leaking but I find a few bolts have backed out
and I have to retorque them. Next time I drop the pan, I guess I need to loctite them.
(If I don't drop the pan, I'm concerned the loctite won't hold or will get into the fluid.)

I plan to change the fluid (not flush, just drain) often enough to keep it cherry clean looking.
You only get about 1/2 the fluid this way, so you have to do it more often to get the same
effect. (1/2)^k old fluid is left after k changes.

The differential fluid should last longer so I'm more concerned with just checking its level
rather than replacing it. To check its level, put a lighted dentist mirror (from the grocery
store in my area) between the firewall and the differential and look into the hole after you
remove the filler plug. Bounce your body weight on the car and look for dribbles (or
sometimes you can see the fluid surface reflection through the hole).

I also had problems with small leaks through the drain plug of the tranmission. Make sure
to use a new drain washer EVERY time torqued to the full 35 ft-lbs (29 ft-lbs for the
differential) or at least flip it over to get a fresh surface between the bolt and hole. If
you don't you'll leak after a few days. Its enough of a pain that I plan to drop the pan,
I won't loosen the plug, I'll just put a drain tub under the back of the pan, crack it loose,
and left it drain through the gap before removing it. Saves my time and a new washer!

patcal · 05-09-2009, 08:16 AM

ericdude,

Thanks for the heads up. I usually use FelPro gaskets on all my cars. What was the filter like? I was told it was just a screen in a metal housing. Not really a fine mesh filter.

retiredat44 · 05-09-2009, 09:46 AM

look at the color of the tranny fluid. Is it look burnt at all? How many miles on it? Take those questions into consideration if you think it could cause problems by changing it. Also, do you know the history of the car?

If there is lots and lots of miles on it, do it... You need to get those microscopic pieces out. Before they really hurt the trans. But, only after checking off the questions asked.

IMHO

patcal · 05-09-2009, 10:45 AM

retired,

I have very little history on the car. Nothing on the tranny. The tranny fluid is kinda dark but does not smell burnt. With 127K, is that lotsa miles? All I really know is it's shifting fine and not leaking.

retiredat44 · 05-09-2009, 07:04 PM

I would hate to say change it, then you have problems, but the only way to check for metal shavings (normal wear shavings) is to take the filter out..

For now I would say maybe... it probably would not hurt since the color is fine and no leaks..

ericdude · 05-09-2009, 10:37 PM

Quote:

Originally Posted by patcal

ericdude,

Thanks for the heads up. I usually use FelPro gaskets on all my cars. What was the filter like? I was told it was just a screen in a metal housing. Not really a fine mesh filter.

It reminded me of the screen in a screen door, except finer (smaller mesh). Similar to the filter
in your power steering pump reservoir. (Drain the reservoir, and look through the hole with
a f lashlight.) As I said, it looked almost new after 60k+ miles; most of the goop was gobbed
on the magnets.