2003 2.5 Z4 manual transmission and diff fluid question

[Donovan303]

Hello all,

I have been reading up on the process for changing the diff and trans fluid in my Z4 and I have a couple questions for those with some more experience with these cars. I called my dealer and they of course told me not to change the trans fluid ever. They also refused to tell me the details of the fluid itself. Interesting since according to this thread:

http://www.bimmerfest.com/forums/sho...t=transmission

It is right on the container.

So here are some details. My car is a 2003 2.5 manual transmission Z4. It currently has 118,000 miles and I do not have service records stating that the fluid in the diff or trans have ever been changed so I must assume they are original.

Shipkiller seemed to state it was unwise to change trans fluid after 100,000 if it had not been done before, but I found others who said it should be done regardless of the mileage. My dealer said if I insisted they would do it but the car must be on a lift and running with a temp probe in the transmission when filling to account for fluid expansion or else the trans could be ruined. I had never heard that before and it runs against what I've read with regard to DIYs.

So should I change my transmission fluid or not? If I do is there any reason I cannot use any API GL-4 75W-80 fluid? The only RP I've found seems to all be 75W-90. Same for Castrol.

As for the differential, should I change this or leave it alone? I'm thinking it needs to be changed as well, with new plugs. However that brings up the questions of fluid again. I see people reporting using RP, Redline, etc... but those are 75W-90 oils.

Does my Z4 use 75W-140, or 75W-90?

I found this in another thread

"Limited Slip Differentials
BMW Synthetic Final Drive Oil (SAF-XJ) --> Google says this is 75/140
(with multi-plate limited-slip differential)

Non Limited Slip Differentials
BMW Synthetic Final Drive Oil (SAF-XO) --> Google says this is 75/90"

And apparently a recommendation from Ron

"Tranny Fluid: Castrol MTF-LT-2, 5 liter
83 22 0 309 031 $128r
I purchase the 5 liter jug from Jay Lilley.

Diff. Fluid: Castrol SAF-XJ, 55 liter
83 22 1 470 080 $800r, 1 liter = $14.55r"

So is SAF-XJ really 75W-140 and that is what I need in the diff?

Thanks,
Donovan

[gcochard]

Your z4 should have SAF-XO in it right now, you can replace with 75/90 like redline, RP, etc. or go with the castrol brand.

EDIT: Also, your link is dead.

[Donovan303]

Cliffhopper,

Thanks for the information. The link is now fixed.

I'm guessing I should change both tranny and diff?

I would really hate to screw up the tranny by changing the oil at such a high milage *if* it is going to somehow cause damage.

This car getting 168 miles a day on it and is my daily driver.

I've no problems with the change procedure itself, pretty straight forward. But I still have doubts based on what I've read as to if I should do it or not.

My steps would be to drain both at operating temp
Replace all plugs
Use API GL-4 75W-80 or 90 (I was thinking Mobile 1) in the transmission
Use SAF-XO 75W-90 in the differential

If this sounds right it seems the diff and the tranny can use the same oil? Which in my case based on availability would be Mobile 1, Castrol, or Royal Purple.

Does this sound right?

[santov]

I just looked in TIS and it says for 2003 2.5 with MECH (manual) just drain from the bottom and refill from the top until pours out. Torque both to spec. Send me your last 7 digits of your VIN if you want me to verify.

The act of changing the fluid will not hurt anything. Using the wrong fluid, overfilling, underfilling etc. could create problems, but I doubt you'd do anything like that.

My advice is to change it ASAP. I haven't researched fluids for a manaul tranny, but the OEM fluid is kinda expensive. MTF-LT3 is $147 for 5 qt jug.

I found this article. I'm sure Redline makes a good compatible replacement.
http://www.redlineoil.com/news_article.aspx?id=13

The diff is easy. Just drain and refill. Redline, Mobil1 are all great. You don't have a LS, so that oil should be low wear (albiet old). I changed my diff fluid at 25k miles, not because the fluid was suspect because I wanted to see what was inside. The drain magnet had lots of break-in material, but the fluid looked fine.

Can you PLEASE PLEASE PLEASE take pictures? We all want to see what the fluids look like.

[santov]

Oh, I think your dealer was thinking of the automatics that needed to be running. That's true since the torque converter has a rather large capacity. But it's not because the fluid expands or shrinks, it's because you need pump the fluid in whilst the TC is in motion to make "room" for the fluid.

[gcochard]

Just be sure that if you DIY, you overflow the fluid on the refill, then let the excess drain completely before replacing the fill plug.

That will achieve the perfect fill level as long as your frame is level.

[Donovan303]

OK, I've got the stuff ready for the diff and will be changing that now, pics to follow.

Santov, I will send you my VIN information so you can verify the trans information. When I looked at the yellow sticker on the trans tonight it says MTF LT1. I don't have a clue what that is and BMW will not say. I have not looked enough online yet to convince myself I have the proper information for the trans fluid so I didn't buy anything for it yet. The DIY here even says use ATF fluid for my year and model.

See here:

http://www.zpost.com/forums/showthread.php?t=79739

So if anyone can absolutely confirm what Mobil, Castrol, etc... brand will work for MTF LT1 I'd love to know.

Diff pics soon.

Thanks,
Donovan

[Donovan303]

OK, here is the result of the diff change.

The car currently has 118,483 miles. It is a daily driver that gets 168 miles a day in a commute. I bought the car used a little over a year ago around 84,000 miles. I didn't get a lot of records with the car, so I do not know when/if this oil has ever been changed.

Here is what came out.



The old plugs:



An old plug vs. a new one. I assume the new ones do not use a crush washer since they didn't come with one and have the blue rubber washer built in.



The oil I went with.

[Donovan303]

Posting once more so I can use PM.

[santov]

Whoa! That fluid looks pretty good for 118k+ miles and there's not much crud on the plugs. Mobil1 is great stuff, it's what the SRT guys use in their giant rear diffs.

[Donovan303]

Santov,

I read the redline article, and also a lot of bad reviews on using this fluid in a manual transmission even though it is recommended. There are also a lot of good reviews as well. Also, I cannot find it locally and it was $42 to ship...

I'm not done looking but that article is interesting. It says that MTF-LT1 and LT2 use the same redline fluid, D4ATF. I've also found that LT-1 and LT-2 are compatible.

This picture shows a container of BMW LT2, and it says right on the side SAE 75W-80 API GL-4



The yellow sticker on my transmission says MTF LT-1 but if they can use the same fluid as LT-2 then an SAE 75W-80 API GL-4 should be fine.

I cannot locate any GL-4 compatible oil locally except RP or the dealership's bottle.

Mobil 1 75W-80 gear oil is definitely not ATF. So what really goes in this transmission? Right now I'm inclined to believe:

1) Redline D4ATF if I can find it locally.
2) Any SAE 75W-80 API GL-4 if I can find it locally.
3) I must buy the BMW oil.
4) Royal Purple, which seems to have good reviews, especially from those who have tried Redline and didn't like it, and it is available locally.

Sorry to keep going around with this one but I really want to get this right.

Also, BMW only sells 5 liters at a time and I think the tranny only takes 2 liters?

As soon as my PM privileges come through I will send you my VIN and you can verify this.

Thanks for all the help.

Oh, and I thought that oil looked pretty good myself.

Cheers,
Donovan

[santov]

I wasn't endorsing Redline. I actually shy away from botique brands. I was just linking that article hoping it would give you alternatives to the $147 OEM bottle.

I am a Mobil1 fan (engine and diff).

I'll look up your DIS info now...

[santov]

LT2 superceded LT1. I'm not sure what LT2 alternatives you have, but here's the TIS procedure, fluid recomendations, and torque specs.

Hope this helps!

[Donovan303]

Thanks Santov! I've got the transmission drain plugs on order and will post pics of that change when they come in, probably mid-week.

Cheers,
Donovan

[Donovan303]

OK so tonight I changed the transmission fluid.

I went by the dealer and picked up the fill and drain plugs they said were for my car. Not even close. Here is a pic of the bag I picked up showing the part numbers.



And the plugs, I never opened them. They were smaller in diameter and not the same thread.



And the plugs that came out of the transmission on my car. These were 17mm, and did not have a crush washer or rubber sealing ring. They just screwed in and I saw no reason to not use them again.



And finally the oil.



This oil was quite thin, about like water. It only took 1 liter to fill the tranny back up to where fluid ran out of the fill hole. I ended up using Purple Power.

Cheers,
Donovan

[santov]

Looks good! Nothing wrong with using the old plugs.

[BTM]

Originally Posted by santov

Looks good! Nothing wrong with using the old plugs.

The plugs are aluminum and should be replaced. The cost isn't prohibitive.