Transmission service on an '03

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Supporting Vendor
May 2, 2004
Jackson, MS
I have read every thread I could find relating to transmission fluid changes, but none I have found address the direct question I have on my '03 LX.

The records from the PO are quite extensive......until you get to the 60,000 mile service mark (for which there are no records of it having been done). Therefore, with the vehicle now having 94,000 miles on it, and with me not knowing if it has ever had a transmission fluid service, what is the board's advice on the "safest" fluid service for a tranny with this kind of miles? Is it best to do the incremental change method (drain the pan and refill at each oil change for the next 4 or 5 oil changes)? Should I do the complete replacement method of having the tranny completely "infused" with new fluid? Or should I do nothing at all due to the miles driven without knowing if the fluid has been changed?

I've heard people talk about tranny problems arising following fluid changes on high-mile transmissions; therefore, even though mine is not really THAT high-mileage, I just don't want to disturb anything inside the unit that would cause me problems on this autobox.........

Thanks for any advice.
When I wanted to change the unchangeable fluid in my BMW, I went to the nationally revered master of that particular transmission who happened to be in my town. His preference is to drop the pan, disable the engine ignition, and turn the engine with the starter to pump most of the fluid from the trans & torque converter. Then he changes the filter, installs the pan, and pumps fresh fluid in. His shop does power flushes, he personally doesn't recommend it.

If we don't have a trans filter to change, I guess I'd just drop the drain plug and follow this procedure.
What is the fluid condition ? Unless it looks like crude you should have no worries. At 94k I say just drain and fill until you feel good about it. Easiest, Cheap, Safe.

Do not allow a shop to use a high pressure system(flush system) on it.

The 80's board has a good FAQ for DIY complete fluid replacement using the transmission's own pump and the tranny cooler hose and some 100 owners have done the same. Takes about 20 Qts of Fluid.

There is no filter, just a reusable screen, low turbulance pan and plug magnet on drain plug.
hello all, great site! i have a 2000lc and i just did my second tranny service. the first was when i bought it with 125k. basically i drained the fluid in the pan and replaced it. after reading about all the tranny problems with '00, this time (138k) i dropped the pan and changed the filter. very easy just messy. bought the filter/ gasket kit at NAPA. it was like $60 also use royal purple fluids in everything on my rig.
From what I've been gathering searching around here and other forums there's a few ways to do the tranny fluid:

- Pull drain plug, empty pan, and refill
- Flushing (pull drain plug and/or cooler line and force circulate/fill new fluid)
- Drop pan, clean pan and filter, refill

The issue with flushing appears to be that it stirs up anything on the filter or in the bottom of the pan and can push it back into the tranmission gears. The preferred way seems to be to drop the pan, clean out any particles or shavings that have collected there, clean the filter, and then refill. However, you can also just drain the pan without removing it and fill with new fluid since that shouldn't disturb anything in the pan or on the filter.

At my 100k timing belt change we just drained and refilled, everything's been fine.
Thanks for all who have replied.

My actual original question was: with potentially 94,000 mile-old transmission fluid what SHOULD I do (if anything) to change the fluid, not what CAN I do. I'm aware of all of the possible ways to change old fluid to new fluid. I guess I'm just concerned about what SHOULD I do to make sure an not "stir anything up." So far, it sounds like I should just drain the pan and fill it back up (maybe multiple times over the next few oil change intervals). It's starting to sound more and more like a "major" replacement (total infusion or flush) may be a shock to the system and a potential hazard. The fluid still looks pretty good, so, unless a lot of you suggest otherwise, I think that's the route I'll be taking.
Either drain and refill or drop the pan and do the full thing. Don't flush without dropping the pan. In my pointing out the options above, I was trying to show the two that may be the best option for you . . .
Transmissions are not damaged by fluid changes. They may be damaged by a high pressure flushing machine. And lots of transmissions on their way out may get a fluid change right before failure when the owner notices problems and tries to do something.

The 2000 model year failures are caused by defective internal parts and are not related to fluid service.

If you drop the pan please take a picture for us showing what, if anything, is in the bottom of the pan.
drain and fill should be good enough

drop and refill is better if you have the inclination

not flush
From what I've been gathering searching around here and other forums there's a few ways to do the tranny fluid:

- Pull drain plug, empty pan, and refill
- Flushing (pull drain plug and/or cooler line and force circulate/fill new fluid)
- Drop pan, clean pan and filter, refill

A dry fill takes 12qts, I suspect that doesn't include the fluid that comes in a factory new torque converter, mine came with several quarts in it.

A drain and fill replaces 3.5qts. So you replace about 1/4 of the fluid with a drain & fill. 7/16 if you do it twice, 37/64 three times, etc. That's for using the drain plug or dropping the pan. Each subsequent drain & fill replaces more of the fresh fluid.

Flushing will replace fluid at about the same rate, flushing 12qts will replace about half the fluid, maybe more depending on how it mixes and flows through the transmission. As the fluid mixes in the transmission, you're replacing more & more new fluid.

You didn't mention the method I recommended, but it should replace 12qts without the fuss of hooking up tubes or hoping to get the pan back on without leaks. You're also not throwing away half your new fluid as you go.

Dnp, Good luck with whatever you decide.
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