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Discussion Starter · #1 ·
So I planning on replacing the filter and fluid in the automatic tranny in my E34 (M30 engine).

But on another forum I saw a few messages that stated if you don't know the vehicles history (such as mine) it could be detrimental to replace the tranny fluid if it has not been replaced ever or for a very long period. The reason being that the little metalic flakes (from wear) actually improves friction and taking it out and putting new fluid in will cause more slippage in the tranny.

Anyone agree or disagree with this theory? I'm holding off on doing mine. I have I'm approaching 163K miles and I do not know the vehicles history.

Thanks!
 

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The theory has been shown to have merit. I wouldn't go as far as to call it proven though. In the event that it's true, I would think new fluid would mean an overhaul; that would be close to a new transmission.
 

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Discussion Starter · #3 ·
Thanks for the info Witeshark.

I was just in the process of doing a Google search and I found a thread from this forum that was started a year ago. It agrees with what you said and some of the things I read.

Funny - I did a search on transmission fluid on this forum before starting this thread and I didn't see this other one. But the results give you everything with fluid or transmission in it.

Here's the thread I found . . .
http://www.bimmerwerkz.com/forum/5-...ransmission-problems-after-service-56591.html

I think I have the owners manual at home, I can see if the previous two owners wrote anything down about tranny service but I think I just might leave mine alone.
 

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There is also a good chance of old fluid gunking up & becoming tacky causing valves & checks to stick in the valve body, causing problems with shifting etc.........fresh fluid & new filter is the way to go!


jb
 

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If you are planning on changing your auto tranny's fluid and do or don't know the history then all you need to do is inspect the fluid and the pan. If they fluid is pink it's fine, light brown is normal wear, dark brown needs to be changed and if it is black or smells burnt then don't change it. If the color looks good and it doesn't smell burnt then drop the pan and look for metal shavings etc. some is normal and is ok but and excessive amount is definitely not good.
if you find that your tranny fluid is black, burnt or has excessive shavings then leave it alone and start saving up for a new tranny, new fluid will do more damage then help.
 

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Discussion Starter · #6 ·
Thanks for the tips Smoothm3.
Mine is more of a light brown - maybe next spring I'll drop the pan and take a look.
It seems to run fine - so I'm probably fine to leave it as it is.
 

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Change it, but don't get it 'flushed out'. In other words, whatever comes out on it's own is it, then you put new fluid in.

Fresh fluid never hurt anything; flushes have -- as that gets all the stuff that might still be holding it together out.
 

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I called a ZF service centre in Germany and they recommended that the trans oil should be changed every 60 - 80k km, and that BMW recommendation to leave the oil in for the life of the transmission, was good for them (BMW), because they (BMW) sold replacement gear boxes.
I don't know of the merits of leaving bad oil in, because logically it will only accelerate the wearing process, but mechanical stuff doesn't always behave in a simply logical manner because of the diverse range of variables.
I changed my oil at 136k km, and so far so good, i've only done about 3000km since then. Good luck with what ever you do.
 

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You can test it by removing the filler plug, it should be level with the hole, not below and not pouring out- dripping is fine. But before you check it refer to the proper procedure I.e. Some want the fluid 30-50 degrees C (operating temp.) and for you to run the shifter through the gears before opening the filler plug. I believe that's what alldata says.
 

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Change it, but don't get it 'flushed out'. In other words, whatever comes out on it's own is it, then you put new fluid in.

Fresh fluid never hurt anything; flushes have -- as that gets all the stuff that might still be holding it together out.
Fresh fluid will hurt the tranny IF the fluid that comes out is black and/or burnt, ask any automatic transmission shop, when the oil is black and/or burnt start saving up for a new tranny and hope the old one will last or a while. It has to do with the particles and debris in the oil, the viscosity of the old oil, the trans seals and largely because auto trans fluid is super high with detergents and they work so well that they will end up hurting.
 

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well i still dont know whats best,logic would dictate a change,as does the guys who know.mine was changed at 5o,000 miles.now 95,000 ang going well.
bretski seems to have heard it from the horses mouth,i would listen to zf.
remember the mileage on your speedos is not often correct after the car has had a few owners,ie you think your doing a swap at 70,000 but its really done 170,000.bmw lend themselfs to clocking.The owner does not always tell the truth when he sells you the car,he may be responsible for change,the difference in value of used cars with big mileages is so great many are tempted.
buyer beware.
 

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Discussion Starter · #13 ·
I bought the car from a friend (I'm 3rd owner of car) and he wasn't sure if the fluid had ever been changed.
The car is a '91 and he bought it in 2001. He would take it to a shop, have them do work, pay for it and leave, he rarely kept the invoices. He gave me the few he did keep but they were for a new radiator, thermostat, but nothing that mentioned tranny service.

My car does have the dipstick on the tranny (I guess some don't) - and the fluid looks OK. Light brown but you can detect a little pink to it. So it is possible that when my friend took the car in for it's periodic maintanence - they performed the BMW recommended service items listed in the manual.

I talked to the shop that did a lot of the work on it and the mechanic just recently went to a computerized system, so he did not have any records prior to that. The mechanic did print out and mail me an invoice he had for my car but it was for hoses, intake manifold gasket and spark plugs.

Real nice guy (the mechanic) - owns the shop and he was very helpful over the phone.
He said he had once changed the fluid in a 740 with high miles and afterwards the car wouldn't drive out of the shop - but he didn't mention the condition of the fluid.

The car shifts fine right now and so I'm not too concerned. So I'll probably wait for next spring when the weather is better for working on the car to look in to changing the fluid - and I'll just to a drain - not a flush.
 

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My car has the GM Strasburg 4 speed tranny. Unlike GM's typical recommendations, BMW recommends changing every 25K miles, which I have done.

Except, the last time I had the tranny serviced, the shop used Pentosin synthetic fluid instead of Dextron. It cost a lot more, but wow, the tranny shifts like a hot knife in butter! I have 46K on this fluid, figuring it would last longer than the non-synthetic fluid, and plan to change it at 50K.

The car has 146K miles on it now, just returned from a 10K mile cross country trip. In used 1/4 qt of Mobil 1 15-50 oil for the entire trip, even with consistent 105+ degree ambient temperatures on the southern route across the US.
 

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Discussion Starter · #15 ·
I've had the car for a little over a year now and it has 166K on it. The previous owner isn't sure if he ever had the tranny serviced. He took it in for the scheduled checkups and he said they did whatever needed to be done. The owner prior to him (original owner) was a friend of his and he also did the scheduled service on it.

The tranny fluid looks pretty good but since I don't know the history on it, I'm a little concerned about having the fluid and filter replaced. I've heard horror stories about trannys that haven't been maintained going bad after a fluid change.
 

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As the factory schedule calls for fluid changes at every Inspection II, it probably was done. IMO, it would have died by now if it hadn't been changed.

My 95 has synthetic fluid in the diff, and calls for changes every other Inspection II. I am guessing that tranny fluid changes could be every other Inspection II if synthetic fluid is used instead of conventional.

I just bought 3 liters of Pentosin ATF1 and a filter kit to change my fluid. Found an internet store in Arizona that had fluid and a kit of gaskets, pan bolts and filter for a good price, 2 day delivery. PM me for the name as I am guessing that forum rules don't allow naming them.
 

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Discussion Starter · #17 ·
Thanks for the info Pete. You brought up another thing I have not checked yet and that is the differential. I should get under and check it out before winter sets in.

I think I know which store in AZ you are talking about - I have bought quite a few things from them as well.
 

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Update on the tranny fluid change

Bentley recommends dropping the large pan and refilling with 3 L of new fluid. Pelican's Site recommends dropping both pans, refill quantity is not stated, unfortunately.

The Filter set comes with new bolts for both pans plus the 2 gaskets, but not the drain or refill plug washers, FYI.

I only got the 3 L of fluid specified by Bentley so only dropped the big pan. Fluid looked pretty clean when draining, but there was some gunky stuff on the bottom of the pan. Magnet had some metal on it, but not very much. The filter appears to be a real filter, not a piece of metal mesh that I found many years ago when I did by 1976 Ford van, so I have changed my opinion about changing it not being important. Glad I did.

I tried to use the oil bong I made from clear tubing (for the diff change and the Porsche transmissions) to fill the trans but found you cannot get enough fluid in the fill hole due to the angle. I still have several OZ left, and the car is telling me it is underfilled.

You will need a oil pump to properly fill the trans.
 

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Update on the trans refill:

it looks like it will take 3-1/2 liters to properly replace what was lost from dropping the large pan. Next time I will buy 6 liters to do both pans.

I bought a pump for < $10 at the auto parts store and it makes things much easier.

You cannot torque the fill plug as there is a control rod in the way, so only a 17mm wrench fits on the bolt.
 

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Discussion Starter · #20 ·
Thanks for the tips Pete.
I had done some reading a while back on changing the diff oil and they say to remove the top plug first.
You don't want to remove the lower plug and drain it and then find out the top plug is frozen and can't remove it.
 
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