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Discussion Starter · #1 ·
Hello All,

I changed my rear diff fluid about 200 miles ago with Royal purple full synthetic 75w140. Someone told me today that I should be running a "friction modifier additive" because it is a limited slip differential (LSD). I called BMW and asked them if they sold such an additive and they told me no, but that the diff fluid for M5's is different from 540's because the difference of an open rear versus a limited slip. Did i do the right thing by just doing the flush with royal purple with no additive or should there be an additive in there? If so what additive do you guys suggest or should I just bail on the royal purple and get stuff straight from BMW? Thanks for any/all imput!
 

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BMW sell an SAF XJ 75W-140 with Friction Modifier (FM).

The stock oil is SAF XJ 75W-140 by Castrol.

I am aware people put in the SAF XJ 75W-140 with FM if they are experience bad diff groaning.

A lot of the E46 M3 owners have had to do this, I know.

I think you are fine, with the correct Royal Purple Oil for our diffs.

Yours wasn't groaning, which prompted you to do diff oil change right ?


Cheers
 

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Ford dealers actually have a small bottle of friction modifier for use in Ford's limited slip differentials. The stuff STINKS, don't get any on your hands! I put one bottle in my diff (mixed in with a quart of R.P. 75/140). Standard disclaimers apply, but I added it to mine, and it seems fine.

Joe
 

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Hello All,

I changed my rear diff fluid about 200 miles ago with Royal purple full synthetic 75w140. Someone told me today that I should be running a "friction modifier additive" because it is a limited slip differential (LSD). I called BMW and asked them if they sold such an additive and they told me no, but that the diff fluid for M5's is different from 540's because the difference of an open rear versus a limited slip. Did i do the right thing by just doing the flush with royal purple with no additive or should there be an additive in there? If so what additive do you guys suggest or should I just bail on the royal purple and get stuff straight from BMW? Thanks for any/all imput!

dont be surprised, when you call up BMWNA you're not talking to the engineers or mechanics just a random desk/cubicle person that pulls up information (probably wrong information)


from what i've been able to gather there's only 1 differential oil{refer to edit#2 at the bottom of this posts}

But 2 part numbers & it's because of different quantities

part no. 83 22 1 470 080
part no. 83 22 1 467 993


tischer bmw lists them like this:

Item Number
83221470080

MSRP
$1,389.23

Core Price
$0.00

Price
$1,111.38

DIFF OIL
55 Liter
XJ
&

Item Number
83221467993

MSRP
$12.63

Core Price
$0.00

Price
$10.10

1 Liter
DIFF OIL


if you want to buy a Castrol Product directly it's

SAF-XJ
75W140
Castrol SAF-XJ 75w-140 fully synthetic final drive lubricant


this is also BMW Approved - likely for older cars
SAF-XO -NOW CALLED CASTROL SYNTRAX LONGLIFE
75W90
Castrol Syntrax Longlife 75W-90 (Formally SAF-XO 75w-90)



edit:

the small bottles of SAF-XJ+FM are likely a literal translation of the name - regular SAF-XJ plus more FRICTION MODIFIER - mixed in by BMW
>i have it in my diff, but i am switching back to regular SAF-XJ; the modifier was for E46 M3 differentials that made noise, and only if they made noise

edit #2:

according to the PDFs on OpieOils which seem to come from Castrol - Castrol's new version of SAF-XO 75W90 (now named: Castrol Syntrax Longlife) is NOT recommended for BMW Limited Slip Differentials

note: these are NOT BMW products they are Castrol products, and I dunno what the dealers in the U.S. use - i am still under the assumption that ALL BMWs use only 1 type of differential oil (SAF-XJ/75w140) and that the BMW 75W90 was phased out for the 74W140 {Verification NEEDED}


CASTROL SYNTRAX LONGLIFE
(formerly) SAF-XO
http://www.opieoils.co.uk/pdfs/castrol/Castrol SAF XO.pdf

APPLICATION

Castrol SAF-XO is specially designed and fully approved by BMW for use in all
BMW final drives fitted with conventional (non limited slip) differentials. Castrol
SAF-XJ should be used for BMW final drives fitted with limited slip differentials.
 

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Mobil1 sells 75w140 fluid with friction modifiers. Available at any Pep Boys. That's what I'm using.
 

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Discussion Starter · #8 ·
I change the fluid because I just got the car a couple of months ago and the previous owner had not changed it during his ownership and the vehicle is currently at 118k. The rear end is making a little noise at higher speeds but really not bad. There is no chattering or binding feeling when turning/accellerating at low speeds. I am going to verify that I put in max gear with friction modifier tomorrow and report my findings tomorrow. thank you all for the quick response and all the input!
 

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> All viscosities of Max-Gear are formulated with hypoid friction modifiers necessary for use in clutch or cone type differentials. No additional additives > are necessary.

Royal Purple Gear Oil
Thanks !! I will use The Royal Purple oils then. I'm in the same case as Lefebv19, I don't know if the previous owners have done anything with the car, I can go back to 04/2009 only in my history, and I only saw engine oil changes (2 times !!!).

So I will give her a full oil change soon :biggrin:
 

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Thanks !! I will use The Royal Purple oils then. I'm in the same case as Lefebv19, I don't know if the previous owners have done anything with the car, I can go back to 04/2009 only in my history, and I only saw engine oil changes (2 times !!!).

So I will give her a full oil change soon :biggrin:
Ditto. Royal Purple seems to be popular, and it's not just a case of using something other or 'better' than OEM, it gets a lot of good reviews on here. Good enough for me.
 

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Discussion Starter · #13 ·
So i verified that royal purple max gear does have limited slip additive. It even says on the bottle. I went to the part store and verified. I probably should have done my due dilligence and went to the part store but i really appreciate all of the help. thanks guys!
 

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Thanks !! I will use The Royal Purple oils then. I'm in the same case as Lefebv19, I don't know if the previous owners have done anything with the car, I can go back to 04/2009 only in my history, and I only saw engine oil changes (2 times !!!).

So I will give her a full oil change soon :biggrin:
I've been using RP for both the transmission and diff for the last 12K miles. Shifting has been noticeably more smooth since the change and I haven't heard a sound from the diff. There's an awesome thread by Timmay77 with pictures if you want to know what to expect (assuming you're changing it yourself). My biggest A-ha when I changed mine.... make sure you can get the fill plug loose before you open the drain plug. Mine were both on VERY tight, and draining the fluid and then finding out you can't fill it would be bad hmmm
 

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I've been using RP for both the transmission and diff for the last 12K miles. Shifting has been noticeably more smooth since the change and I haven't heard a sound from the diff. There's an awesome thread by Timmay77 with pictures if you want to know what to expect (assuming you're changing it yourself). My biggest A-ha when I changed mine.... make sure you can get the fill plug loose before you open the drain plug. Mine were both on VERY tight, and draining the fluid and then finding out you can't fill it would be bad hmmm
It's this thread that convince me to do the oil change. I will check the fill plug twice :D
 

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I am changing both my output shaft differential seals, since they have a small leak. My plan is to use Royal Purple.

Is there any reason to go OEM? I did read that some e46 m3 owners exhibited some gear noise with aftermarket products, but don't know if it was oil related for certain.

Thanks
 

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I am changing both my output shaft differential seals, since they have a small leak. My plan is to use Royal Purple.

Is there any reason to go OEM? I did read that some e46 m3 owners exhibited some gear noise with aftermarket products, but don't know if it was oil related for certain.

Thanks
I am using M1 75w-140 in my diff. No issues.

Regards,
Jerry
 
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