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Discussion Starter #1
Hi there,

(Disclaimer: I am a geek.)

So I am flushing my transmission fluid using the so-called 'turkey baster' method. I get to wondering how many bottles of Mobil 1 ATF I should buy to replace most of my fluid using this technique.

So I created a little spreadsheet to work out what percentage of fluid is replaced after one, two, three or more flushes. Based on my experience, a 1 litre bottle of ATF is enough to refill the completely drained reservoir three times, so I am assuming that it is possible to get 0.33 litres of new fluid into the system each time. I have not been able to find a definitive answer to the total system capacity but based on a few posts I have found I believe it is a little less than 2 litres, let's say 1.5 litres.

I would attach the spreadsheet, but I don't think .xls attachments are allowed here.

But assuming 0.33 litres reservoir and 1.5 litre system capacity, here are my results. The left column is the number of times the reservoir has been emptied and refilled, the right column is the percentage new fluid in the system:

1 22.00
2 39.16
3 52.54
4 62.98
5 71.13
6 77.48
7 82.43
8 86.30
9 89.31
10 91.66

As you can see, you run into diminishing returns because after a while you are removing more new fluid than old. The reservoir capacity is 22% of the system capacity by my numbers.

So after one bottle of Mobil 1 ATF we have replaced 53% of the fluid, and after two bottles 77%. Three bottles would get me up to 89% new fluid.

(Told you I was a geek.)
 

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The real question is whether or not that method is worthwhile. Draining the system completely might be more favourable given how long it would take to "baste" above 90%. A BMW mechanic friend of mine has also confirmed this.

Nice car, i happen to have the exact same one. I was considering whether or not to baste mine too
 

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Discussion Starter #3
Can't see there is much to lose. Three bottles will get you to around 90%. I am not up for removing the return line and fully draining the system that way.

I used expensive Mobil 1 synthetic ATF, but I think any old ATF will do.

Nice car you have! Seems identical - 320i, 5 speed, sport package, no other options. Japan Red. Looks like you have different wheels than I do (style 43 here, I think). What year is yours?
 

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2003 manual, with sunroof and heated seats. Built in Feb 03 and have owned it from new. Came with style 43 like yours, which i use as winter wheels. For summer i have d-force LTW5s 17x8.5 all around with Direzza Z1 tires.

There are many parts of the car that I work on myself, but i find that the really oily bits don't tend to save you tons of money. Especially if you have good mechanics that are reasonabe. But of course, anything you can do yourself is still worthwhile for a job well done.
 

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1 bottle 1 litter is enough. The keys is after each suck out and refill. Drive the car enough so the new fluid is completely mixed with the old. So really doesn't matter
 

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Well each time you empty and fill the reservoir, it will dilute with the rest of the fluid after your turn the wheel a few times. One litre should be good to get it to a cherry colour red again.
 

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I did the same calculation for the coolant flush - just drain the coolant at the bottom and refill with distilled water, running engine a few mins and repeat a few times. Last add in 1 gal of straight undiluted BMW coolant. Works out for me and no engine block drain with messy coolant splash.

For the power steering fluid 50% exchange is good enough. I did with a liter of pentosin ATF.
 

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Discussion Starter #8
My calculation assumes that each time you add a new reservoir-full, you mix the new fluid completely with the old.

I turned the wheel 10 turns lock-to-lock each time.
 

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Discussion Starter #9
Hi jst -
No sunroof, no heated seats on mine. I have the sports package (wheel, seats, suspension, 16" style 43s). I don't have auto climate control, multifunction wheel, cruise, OBC, or any of that other stuff most E46s have in North America. I like my car more minimalist. I wouldn't mind fog lights though ;)

I have another set of 16" (non-BMW) rims for winter tires.
 

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you know 56% of all statistics are made up right? At the dealer, we use about 2 quarts of fluid to flush the system. some use the special suck and fill machine, I dont waste my time with that, turkey baster all the way.
clint
 

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you know 56% of all statistics are made up right? At the dealer, we use about 2 quarts of fluid to flush the system. some use the special suck and fill machine, I dont waste my time with that, turkey baster all the way.
clint
you disappoint me and are a discredit to the trade.
 

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Discussion Starter #13
Well you say 2 quarts, I ended up calculating 2 litres, which is pretty close.

2 litres with the turkey baster will replace around 75% of the fluid, assuming good mixing between each empty / refill.
 

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The key to this method of easily maintaining a healthy system is to do this procedure once a year using only one qt. I use Redline D4 and the fluid never gets a chance to turn brown. If you allow the fluid to go bad and dirt to build up, it's a whole other deal! 165K and still working fine!
 

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Question.. Why cant you just suck up all the fluid with the baster till the reservoir stops refilling itself and then just go to town with the new stuff?? :eek:

Also, do you think its a good idea to replace that filter in the reservoir too?
 

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My figures from an old post of mine:
Assuming a 1 litre capacity & a 300ml extraction each time
Extraction Old New
1.............700 300
2.............525 475
3.............394 606
4.............295 705
5.............221 779

=78% new ATF after 5 swaps.
 

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Discussion Starter #17
Em54: Not sure I understand but the issue is that the reservoir is only about 1/3 litre and the system capacity is more like 1.5 to 2 litres.

Steve330: We did the same calc I think, but I based it on 2 litre system capacity, not 1.
 

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Em54: Not sure I understand but the issue is that the reservoir is only about 1/3 litre and the system capacity is more like 1.5 to 2 litres.
Yeah I get it now. I was just under the assumption that the reservoir keeps refilling itself up if your pump is operating correctly. That shows that theres circulation and its working. Got that from a youtube video last night.

But anyway, I can use this right? I couldn't really afford the synthetic stuff but I also read the car really only calls for Castrol Dex3 Domestic ATF. Well this one here doesn't say Dex3, it says "DEX/MERC Domestic Multi-Vehicles" but it was in the Dex3 section and says on the back you can't use in a Dex4 system, so this is what I needed right? They also had a Valvoline right above it that actually said Dex3, but I figured I would go with the Castrol since Im a bit of a Castrol fan. So am I good to go with this stuff below?



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Discussion Starter #19
I am no oil guru but think it is ok as long as it meets Dexron-III.
Power steering isn't too demanding on fluid I think.
I just used synthetic just 'cos. (at $20 / litre)
 

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I am not sure if flushing power steering is even worth the effort. I just changed my fluid last month and 3 days ago my power steering pump failed. Ended up having to dump all the new fluid and put new again into a new pump.
This damn pump's pulley axis just broke off. The pulley just falls out of the pump. I am not sure if this is a matter of fluid, I think the metal used to make the pump is weak.
http://www.youtube.com/watch?v=AKie4V1mtNE
The fluid will probably outlast the pump itself.
 
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