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Old 11-06-2010, 02:41 PM   #102
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Originally Posted by james2538 View Post

This is a Frequently Asked Questions guide for draining and refilling your Automatic Transmission Fluid in your BMW.

Why should I change my ATF?

What would make you want to deal with the hassle of changing your ATF? Well, to begin with, if you plan on keeping your car past 100,000 miles it is an excellent idea. Changing the fluid extends the life of AT just like it would any other component. Not maintained, these ATs have a high rate of failure.

Changing the ATF also results in much smoother and quicker shifts. It will bring your car to feeling like new! Reverse will engage quicker and you will prevent those embaresing moments when reverse doesn't work.

It will also save you money if you don't have to change out the transmission every 100,000 miles.

When should I change my ATF?

Before the "lifetime" fluid, BMW recommended 60,000 mile ATF and MTF changes. I suggest following this recomendation. If you are a little more strict on maintainence and aren't using the OEM fluid (this stuff is expensive to do often and was designed to last a long time) then you can go on 30,000 mile intervals.

If your car has never been changed and you are past 60,000 miles, then now is the perfect time to change out the fluid.

If your vehicle has already started having symptoms of a dead AT it might be too late. Do not expect a miracle to happen if your reverse goes out. It might be worth a shot, but keep in mind that the money spent on a ATF change could have gone towards a new transmission (Use cheap fluid if your transmission is doomed). Please do not blame it on the fluid change if your AT ends up dieing.

I heard changing my ATF can cause "non-warrantable transmission failure", is this true?

This is pure bogus. Since when does preventative maintainence hurt anything? If it can cause failure then why do certain dealers change it?

There are some examples where people have decided to do an incomplete fluid change, their transmissions fail, and they blame it on the change. If you follow all the steps carefully, replace the filter, and use the correct fluid you will be fine.

I heard it is a bad idea to change the ATF on a high-mileage vehicle, is this true?

Better late than never. If your transmission has started descending downhill you might want to pass, but plenty of people have changed there high mileage ATs with superb results. The highest mileage change currently recorded is a 160,000 miles.

Be aware there is a greater risk with changing at higher mileage as the AT has been running on poor quality fluid and has more gunk inside.

If it should be changed, then why does BMW call it "lifetime" fluid?


If BMW can have customers believe that the transmission never needs to be maintained for the life of it, people will be more inclined to purchase the car (BMWs have a reputation of being expensive to maintain).

*BMW has recently revised this lifetime policy to be 100,000 miles.*

What is the difference between the ATs?

Different ATs were used through out the production of the E46 design. They were produced by either ZF or GM. To find out your specific AT, look at the bottom of your ATF pan. There will be a color-coded label. Use the link "Transmission Guide" to match up which AT is in your vehicle. You can also use the link to figure out which model you have by build date (However, this is less accurate).

Since different ATs were used in the E46 chassis, different fluids and filters were as well. Once you figure out your AT model you can find out the supplies. The tools used in this DIY also differ among ATs.

Where should I get my ATF changed?

You can do it yourself right in your driveway! If you have read over the DIY and the task intimidates you too much or you would prefer not to have a runnning vehicle over your head, then take it to your independent BMW mechanic. If you do not have one, now is the perfect time to find a reputable one in your area. This is a service that dealerships will generally charge ~$500 for, if they are willing to do it at all (most dealerships believe strongly in the "lifetime" fluid). AVOID QUICK CHANGE PLACES AT ALL COSTS. This is not a jiffy-lube service, your transmission will almost certainly die.

Which ATF should I choose?

Many different ATFs are available on the market. BMW warns against using non-OEM fluid in the transmission, as it can apparently cause transmission failure. The problem lies in that the BMW OEM Fluid is $$$. There are alternatives to the fluids but I will not go into depth here. Research yourself and choose what risks (if any exist at all) you are willing to take. Decide on a fluid that is right for your vehicle.

I personally chose to stick with the BMW OEM fluid, as it is impossible to get all of the fluid out in a drain-and-refill service. The torque converter will always contain some. Ways to get around this include a flush (possibly loosen gunk), back flowing with new fluid, or multiple drain and refills. There is as much controversy surrounding the fluid choice as there is the change itself.

I would also not recommend going against the BMW OEM fluid if you are doing the service under warranty, as BMW states "Use of any other oil will cause a non-warrantable transmission failure!" If you are out of warranty, do whatever the hell pleases you!

Excellent Fluid Discussions:
"Lifetime Fluid"
Redline D4 ATF vs. OEM

How do I change my ATF?

Follow my DIY! If you do not have a GM Tranny there are links to multiple other DIYs.

Help! My AT died, what should I do?

It has finally happened to you. Your choices remain between:

1) AT path again
2) Manual Retrofit

If you choose to go the AT path again, you can pick up rebuilt units for around $2000. It is not advised that you service the transmission.

If you choose than manual retrofit path, be aware you are taking on a massive project. There is more than just the transmission that needs to be changed. It is a general $4000 estimate for the switch.

There is alot of information on this subject so search around.
I have 170k on my e46 have not changed the AT fluid I might just do it now. Thanks for the write up.
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