What is the perfect transmission fluid change?

[Brandon Meats]

I've been checking through a lot of the threads on the site about transmission fluid changes / flushes on the 4T80E automatic transmission. I'm gathering up mixed reviews on what is better, some myths on fluid exchangers, and not much on the filters on these cars. Anyways I just broke 90K on my 2000 seville and bought 15 qts of a reputable name brand synthectic ATF. I bought 15 'cause I used to work at a local garage and that's about what it took to do a complete flush in a similar car. Usually in similar vehicles we would do a flush, or drop the pan and change the filter and top off with new fluid. My plan was to do the best of both. Drop the pan, change the filter top off the fluid with some cheap stuff, then flush it out with my good fluid. The more I read on these threads, it seems as the filter isn't really intended to be changed except during a rebuild. Is this due to the fact it's not necessary or it's a pain in the you know what? I have access to this shop to use a hoist and the machine to do the work myself. What's the best way to go about this job. I don't mind spending a few extra bucks for something if I know it's beficial in the long run. I always buy top of the line products for my cars and take very good care of them. The fluid level is good, and the car has no driving issues. I'm just very big on preventative maintenence.

All in all, what's your take? Change the filter or don't? Flush the trans or don't? (I know with dropping the pan you only change about 1/3 of the total volume) I also saw something about the "bucket" trick that I've heard of some old timers at shops doing. Whatever you feel is the best way, I'd be very appreciative of any advice. I don't want to get too far in over my head, but at the same time I want that piece of mind knowing that it was done the best way possible. Thanks for the help!

[Brandon Meats]

Also, while I'm under there, does the differential use a fluid like a traditional style rear/front end? If so, what weight and capacity generally goes in there?

[Ranger]

If you want to change the filter, you'll have to drop the drivetrain and open the trans. Just clean the two screens in the pan. Use the bucket method if you want to get all the fluid out of the TC. Don't forget about the hidden drain plug to drain the side cover.

[dwight.j.carter]

I had good luck with my last car doing a flush. On my 2000 though it is getting due and I am leaning towards flush again. I know Ranger you prefer the change method.

[Ranger]

I guess you can get away with a flush or "fluid exchange" IF it is done correctly. See the Guru's comments about that in the Technical Archives. The other thing I don't like about that is that the pan and the magnet do not get cleaned out.

[JimD]

Originally Posted by Brandon Meats

....I also saw something about the "bucket" trick that I've heard of some old timers at shops doing.

I'm something of an old timer but not in a shop of any kind. I advocate the "bucket" method simply because that method does not require the case to be opened. Not to mention tranny fluid dripping from your elbows.

For your year-model, the so-called filters in the valve body area are nothing but fine mesh screens. My position is; do not open the case!!

Unless your car has been towing a trailer across the Mojave in August, I'll bet your TRANS FLUID LIFE display is still above 90%! This indicator is almost exclusively decremented down as a function of transmission fluid temperature.

Replacing your tranny fluid with DEXRON VI (synthetic) specification fluid will certainly not do any harm. But opening the case is another story.

[dwight.j.carter]

the trans indicator resets at power loss...

[Brandon Meats]

I'm assuming the filter isn't accessible with the trans in the car. I thought something might be up because no local parts stores carried a filter. Special order only. Usually in that case it's not common maintainence. So how about dropping the pan, cleaning the magnet and screens, reinstalling the pan with a new gasket, then doing a fluid exchange? That way I won't need to remove the hidden plug. Less mess, but a more complete job? The pan has some weeping going on or something. The last time I changed oil I noticed some dampness on the pan. I figure the pan should be removed so that I could at least put a new gasket in there and see if it dries up under there. Nothing leaking, just being way too anal about my car like usual. Ay ideas on the diff? Does it use a gear oil or is it lubed by the trans? Thanks!

[Ranger]

Ay ideas on the diff?

Differential? Ain't no such animal under there. That's why it's called a transaxle.

You could drop t he pan and clean it and the magnet, but as long as you are there you might just as well pull the hidden plug. It won't make any more of a mess than draining the oil. The mess comes from dropping the pan.

[submariner409]

The entire transaxle/final drive is lubricated with DEXRON -VI or -III depending on how long ago the dealer did your fluid change.

Take the advice of others and stay out of the transmission case. If it ain't broke, don't fix it.

[pimpdaddycaddy91]

I just did mine a month or so ago going off of a post here youve probably read. All I did was drop the pan and pull the tiny little plug by one of the screens out. I got 9-10 quarts out of it by pulling that plug and with what was in the pan. I think the capacity is 13 but not sure. So I was happy getting that much out without doing a flush. I then cleaned the screens off and the pan and magnet. The filter is not accesible from below, you have to have the trans out to change it. I filled her up with fresh Dextron VI and that was it. I was scared away from having it flushed and I didnt want to do the bucket trick. Putting the new Dextron VI in also made it seem to shift better and smoother.

[Brandon Meats]

Think I'll narrow it down to this: I'll pull the pan off, clean it and the screens. Then buy a new gasket and reinstall the pan. Now do I still take the hidden plug out and drain that? My overall intention is to change as much of the fluid as possible. Leaning towards the bucket method. This way I can clean the sediment out of the pan and flush all of the fluid. Might be a little extra work or money, but hey. When you only do it evry 50-100K, what's the few extra bucks? Any pointers with the bucket method? Do you pull both coolant lines off? Where are they located?(amsoil says on their website to pull them both. Doesn't make sense, I would think you would only pull one seeing as it's a feed and return) Which one do you pull? Do I need to top off the fluid before running the engine, or is it safe to start the process a few quarts low from the pan removal? The last cars I messed around with on something similar were RWD camaros, mustangs, etc. First time I would have done this on a FWD. Plus it's my Caddy and don't want to mess up my baby. Thanks for the help!

[mtflight]

Originally Posted by Brandon Meats

Think I'll narrow it down to this: I'll pull the pan off, clean it and the screens. Then buy a new gasket and reinstall the pan. Now do I still take the hidden plug out and drain that? ...

Any pointers with the bucket method? Do you pull both coolant lines off? Where are they located?(amsoil says on their website to pull them both. Doesn't make sense, I would think you would only pull one seeing as it's a feed and return) Which one do you pull?

Do I need to top off the fluid before running the engine, or is it safe to start the process a few quarts low from the pan removal?

yes, the hidden drain plug has extra fluid in there.

I did the top hose, into a bucket... I tied it into a clear hose, so I could see the color...

simply idle the car as you pour fresh fluid in

the guru said it was ok if it ran a little low and the pump sucked air, if you weren't able to keep up.

I'd say don't start too low, just to be safe.

Obviously remember to check the level with the car idling, on a level surface, as per the owner's manual.

[Brandon Meats]

So today I changed the transmission fluid. Got the car up on a hoist, dropped the pan, removed, the screens, pulled the drain plug and cleaned the pan. There was a little sediment on the bottom of the pan, a glob on the one screen, and some gunk stuck to the magnet. Cleaned all of it out. My new pan gasket came with new screens, so I tossed the old ones and installed the new screens. Installed new pan gasket and torqued the bolts in the pattern as the service manual instructed. Lowered the car and removed the top line. I put a fitting from the flush machine into the radiator and put a piece of rubber hose down to a bucket. Started the car and watched it pump out as I kept adding to the dipstick tube. Got done, reconnected the lines and topped it off. All in all I pumped about 15 quarts of AmsOil and 1 quart of Lucas transmissoin fluid through the whole system. Time consuming (about two hours taking my time), but a fairly simple task without a lot of tools. Now I've got good fluid, a new pan gasket and I should be good for another 50-100k. The pan was weeping a little around the old gasket, so this should fix most of the problem. Getting underneath the car I found out that the steering rack may be leaking a little bit, but that's another job for another day. Thanks for all of your help guys! It's greatly appreciated.

[PupFromCleveland]

Iv got 112k on my 2000 seville and im guessing its time to do a tranny service
I am just debating on weather to have it flushed or just have it drained and have the filter screan replaced
I notice that it shifts hard if im just sitting there and i take it from backing out of the drive way and then when i shift into D i feel a hard shift for a second is that normal
other then that when im on the highway it crusies great not problems when shifting

what is better should i take it to eh dealer and have them flush it

or should i go to my regulare mechanic who does not flush and just drained and replaced the filter