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Discussion Starter #1
So I'm thinking about doing a transmission flush on my 2005 330i zhp automatic soon and I was curious as to what I absolutely need to know going in.

Specially, upon reading the preventative maintenance thread, one fellow fanatic suggested this:
I have an auto, so I can't speak for the manual trannies. BMW says this is lifetime fluid, but that's a crock of horsepoo. I changed my step fluid before 60,000 miles. Reason being, that seems to be the general consensus "threshold" for step tranny failure. There have been many reports of people going to change their auto tranny fluid after 60,000 miles, and having instant failure. The reason being, by that time, sludge has built up, and putting fresh fluid in it will dislodge it and cause the tranny to fail. Do it before 60,000 miles, and you should be ok. After that, every 30,000 miles should be good. Again, this might seem like over kill, but as sensitive as our auto trannies are, it cannot hurt. I recommend Redline fluids once again, and changing the transmission gasket while you're at it.
This advice concerns me because I haven't changed my fluid yet (currently at 80k). What I'm asking is there any tricks or tips to avoid this "instant failure" kpeng speaks of..?
Anything helps.
 

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How do you avoid instant failure? You DO NOT flush. You simply drain and replace. Make sure you top up the fluid correctly (something about heating up the trans to running temp)
Flushing the system is the death of these transmissions as far as my research has pointed out.
 

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Ok well what exactly is the difference between a flush and a drain?

I was just planning on buying the transmission filter kit and changing the fluid. What is that classified as..?
 

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Ok well what exactly is the difference between a flush and a drain?

I was just planning on buying the transmission filter kit and changing the fluid. What is that classified as..?
That sounds fine.
A flush is when you flush all of the old fluid out. Think bleeding your brakes. Or plunging a toilet. Apparently there's stuff in the lines, that if knocked loose, can ruin the trans.
I have a theory that if you flushed, filled, flushed, and refilled that it would be ok. But that's simply a theory and has no experience or backing.
A simple drain and filer change should be fine. As far as I know a lot of people do that without issue. But ymmv
 

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This is not exactly a DIY but from my personal experience, doing a BG tranny flush with BG synthetic fluid, followed by clearing adaptions out of TCU will greatly extend life of the transmission and will improve shift quality. I would find a reputable and trustworthy independent repair shop and have them do it. Also have it checked whether there is a software upgrade available, which also improves downshifting 3-2 and 2-1. We do these services at our repair shop on regular bases.


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There are some good videos on Youtube about doing the flush. Here is one I was going to do myself http://www.youtube.com/watch?v=TIMSzaPRxYU. What I did first was crack the drain plug and see how the fluid looked. Since it was reddish and looked pretty clean I don't feel too worried about a flush. If the fluid looks brown or darker, the general suggestion is to not flush.
 

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This is not exactly a DIY but from my personal experience, doing a BG tranny flush with BG synthetic fluid, followed by clearing adaptions out of TCU will greatly extend life of the transmission and will improve shift quality. I would find a reputable and trustworthy independent repair shop and have them do it. Also have it checked whether there is a software upgrade available, which also improves downshifting 3-2 and 2-1. We do these services at our repair shop on regular bases.


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Changing tranny fluid with a fluid drain and fill is a simple DIY that anyone can do!
 

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Use Castrol Multi Import transmission fluid.
 

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With only 2 posts, I hope you've done some (or plan to do some) reading on this subject. You should determine the manufacturer of your transmission, and use the same or a compatible fluid to refill it. There are many opinions and ideas on this matter. Use the "search" towards the top of each page, as this has been discussed frequently.
 

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Discussion Starter #11
Yeah thanks this all helps. My terminology was off when I said "flush" I was implying just changing out the filter and fluid. I have been reassured that doing just that shouldnt stir up any issues. Just didnt want to bark up the wrong tree here.
 

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There is nothing wrong with a tranny flush any way. All you are doing is replacing all of the fluid instead of only half of it like when you do a drain and refill. I think it's the term "flush" that freaks out the unlearned. They think flush like a toilet. Really all you do is use the tranny's own pump to pump out the old fluid while you manually pump in the new until all the fluid is replaced.

I did a flush on my Toyota pickup but only did a drain and fill on the ZHP. Both run great and shift like new.
 

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There is nothing wrong with a tranny flush any way. All you are doing is replacing all of the fluid instead of only half of it like when you do a drain and refill. I think it's the term "flush" that freaks out the unlearned. They think flush like a toilet. Really all you do is use the tranny's own pump to pump out the old fluid while you manually pump in the new until all the fluid is replaced.

I did a flush on my Toyota pickup but only did a drain and fill on the ZHP. Both run great and shift like new.
Funny everyone else believes a flush is hooking it up to a machine and running some kind of chemical thru it to clean it out.

Do some research online and see what problems people have had after doing a "flush".
 

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There is nothing wrong with a tranny flush any way. All you are doing is replacing all of the fluid instead of only half of it like when you do a drain and refill. I think it's the term "flush" that freaks out the unlearned. They think flush like a toilet. Really all you do is use the tranny's own pump to pump out the old fluid while you manually pump in the new until all the fluid is replaced.

I did a flush on my Toyota pickup but only did a drain and fill on the ZHP. Both run great and shift like new.
:facepalm:


flushing stirs up debris in tranny, do it if you like, it, i never have and never will
 

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:facepalm:


flushing stirs up debris in tranny, do it if you like, it, i never have and never will
Pumping out the old and pumping in new fluid is no harder on a tranny than what the tranny already does while it pumps the fluid around. I don't know about running any harsh chemicals through the tranny. I don't recommend it.
 

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Pumping out the old and pumping in new fluid is no harder on a tranny than what the tranny already does while it pumps the fluid around. I don't know about running any harsh chemicals through the tranny. I don't recommend it.
I think you are using the wrong term for what you are doing.

Flushing is using a machine that pushes a chemical through the tranny to clean it out and then pumps in the new fluid.

You are referring to something else.

Please tell us how you use the tranny's pump to change the fluid.
 

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I flushed my XI trans at 80k with the BG machine and had no problems.
It uses the transmission pump itself to replace the old fluid with new. No chemicals are used.
I dropped the pan and changed the filter. I then topped off enough to avoid any damage then flushed it untill the fluid in the recovery tank started to flow clean.
I just sold it with 105k on it and still going strong.
 

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The only "flush" machines I have heard of or used just exchange the fluid while the car is on at idle. BMW uses the most magnets I have ever seen on their pans so I wouldnt worry about debris but Im more of a fan of dropping the pan, cleaning it and using a new filter and gasket.
 

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Pumping out the old and pumping in new fluid is no harder on a tranny than what the tranny already does while it pumps the fluid around. I don't know about running any harsh chemicals through the tranny. I don't recommend it.
The only "flush" machines I have heard of or used just exchange the fluid while the car is on at idle. BMW uses the most magnets I have ever seen on their pans so I wouldnt worry about debris but Im more of a fan of dropping the pan, cleaning it and using a new filter and gasket.
Well the ZF has many magnets, but the GM only has one.
 

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There indeed is nothing wrong with just draining and refilling it, however only part of the fluid is replaced with drain/fill technique. As far as stirring up debris while flushing I simply do not see how it is possible, at least with the way that I am familiar with. Machine that we use is simply hooked up to one of the cooing lines and transmission cooler to allow fluid to flow through it, is then filled with 16qts of appropriate fluid and then car is ran at idle, while used fluid is pumped into the fluid exchange machine by the transmission itself, it pushes new fluid in. So there is no external pressure or any chemicals that is being introduced into the system.
 
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