confab

It'll hold about a gallon or a gallon and a half with a fluid and filter change. (Little more if it sits overnight, as the converter will drain back some. Little less if it is hot/recently driven.)

The problem with high mileage fluid changes is plaque. Transmissions wear and this stuff gets stuck in passages and in your cooler, and since ATF is incredibly detergent, it washes it loose sometimes and sticks something (Usually the governor in older models and NOTE: You car has one of these.) and it stops shifting and then people who don't know what they are talking about convince you to rebuild it at the cost of thousands, when all you really needed to do was clean the governor or the controls.

I personally would do it because I am big on fluid changes, but having said that: if it messed up I can fix it myself and it won't cost me a fortune. Most people don't have this luxury.

If it really bothers you, you can suck out a couple quarts at a time, once a week or so and replace them.. Thereby slowly changing the fluid and when the condition looks pretty good, you can yank the pan and do the full fluid change just as you normally would, with greatly reduced risk.

Like I said, I would just do it and it is probably not a huge deal and there shouldn't be a tremendous amount of "plaque" in a healthy transmission anyway. But, if it scares you you can do the incremental method and be "safer"

1993C4LT1

not to hijack. But confab, how often should we change the fluid? My trans was a rebuilt May 2015.

confab

It's cheap insurance and ATF is cheap, so I do it frequently.

Normal use? I'd do it every 40-50 maybe.

Hard use? 25-30.

Transmissions are different from engines. They run hard. They have bushings and thrusts that wear. Metal planetary gears that run together. Stuff like that. They do generate a little debris.

The fluid is a clue to transmission health also. Prematurely "Dirty" fluid indicates problems that fresh fluid will not solve.

So, it is nice to see it an be able to anticipate problems that may be on the horizon.

confab

PS: Always bear in mind that, unlike engine oil, "dirty" transmission fluid is not the result of combustion.

There's something IN THAT FLUID that is causing the discoloration. If it is burnt, it is because you cooked it down. Etc.

It's not to be gauged like dark engine oil, which is subject to completely different forces.

aklim

I would think the way to gauge either fluid is by a analysis and not a SWAG by vision or smell

1993C4LT1

Awesome info man, thanks a ton.

confab

Well, you can do that. It is probably more beneficial with engine oil however. There is much more in play with the engine.

In the transmission, no fuel contamination to give away problems. If you see glycol, there's only one way it got there. There's no combustion sneaking its way past valve guides or piston rings to worry about. Etc.

You can take (and pay for) a science approach, but in practice it is pretty simple to diagnose emerging internal pressure control or component failure issues from observation.

IMVHO.

confab

PS:

In the interest of full disclosure, I own a transmission shop in the greater Cincinnati area.

15 years in business now.

JrRifleCoach

50k or 5 year change intervals for all my vehicles.
While the pan is off stick a small speaker magnet in the pan.
Some assurance to capture steel grindings before the filter.

aklim

I'd get a magnet that is made for it. https://www.amazon.com/ACDelco-29535...ion+pan+magnet

mdz66

Many times there may be issues that can only be seen inside the pan. If you remove the pan and find anything not normal atleast you know. If you wait till you have issues chances are its too late.

aklim

ABSOLUTELY. I change my fluid every 60K at the latest. I have an MB using a 722.6 trans that I got at 55K and it is up to 480K now. Speaks volumes since most of my transmissions die way before that. Yes, I don't deny that I tend to beat the trans, among other car parts a little. Those are changed every 30K. I drop the pan at 30, flush at 60 unless it has a drain plug on the TC. Then it is just drop pan, drain every 30.

confab

It really is an indispensable tool.

When you do regular fluid changes and open the pan you will see one of about 4 things, and they tell you everything you need to know.

1) Good fluid.
2) Burned fluid accompanied by clutch material = Slipping component.
3) Excessive Metal Debris = Component failure in progress.

I would add water/coolant intrusion to the list, (pink foam and rusting) but when that happens the damage follows so quickly it isn't usually something that will you will discover during a fluid service. It won't last that long.

86C4Z51

So the torque converter holds 3.8 qts but Cliff and someone else said closer to 7. I don't recall; it's been many years now since I did mine last.

That said, I saw some ATF on the garage floor the other day and that means it's time.

BTW, for auto trannys, if the fluid stays pink and bright, you really don't need to mess with the tranny at all.

aklim

7 total I can go along with. 7 in the TC is kinda stretching, I would think.

Depending on what is leaking. Could be a line or a seal. Hard to say without looking.

I wouldn't. I'd still dump every so often and not go by color as opposed to an average lifespan based off what the results of my use say.

JrRifleCoach

When I had the 700R4 rebuilt, IIRC the complete fill was close to nine quarts.
That's for a completely empty TC and trans.

93jockey

pretty sure that's Liters and Pints

bullguts

Got mine rebuilt and serviced at a workshop and they use full synthetic transmission fluid , funny thing is that it does smell a bit burnt , actually had to take it back twice within the 12 months warranty as well .That part of the C4 seems to be working fine now . Cheers . Ps if you don't know where the dipstick is PLEASE take it to a proper workshop .

JrRifleCoach