Limited Slip Differential Fluid

[gcw206]

I have a Limited Slip Differential in my 1969 280SL, and am having trouble sourcing the correct fluid.  The BBB states, "Use Special Hypoid Oil", but I cannot find a MBZ P/N anywhere in any of the reference books that I have.  I was told that  MBZ #A 001 989 33 03 12 is what I need, but that looks pretty thin.  Before I drain and replace, is this the correct fluid?  Thanks, Galen

[kampala]

That is the same product I bought from Tom H. at the Classic Center (A 001-989-33-03-12).  He looked it up for me while I was in his office in Irvine.  As I recall this is the replacement oil Part Number for the LSD and is used in other diffs.  I had similar concerns as you as my local non-pagoda Mercedes mechanic thought I should double check as it seemed very much like regular diff oil.  After confirming with Tom Hanson, thats what we put in. 

[gcw206]

Thank you; that puts my mind at ease.  I couldn't find the number listed anywhere, and I didn't want to put in an incorrect fluid. 

[capcgn]

The number is wrong, it is normal hypoid gear oil, not for limited slip axle.  The rigth number is A001989520310.  It is Castrol CASTROL SYNTRAX LIMITED SLIP 75W-140. Or you use mineral Oil CASTROL AXLE Z LIMITED SLIP 90, this was in the axle when the car was new.

[Benz Dr.]

I used a synthetic 75 W 90 gear lube with a tube of AMSOIL LSD additive for good measure. LSD will make noise while turning at low speeds and I believe this to be the clutch plates slipping enough to allow for two different wheel speeds.

[Bonnyboy]

Not to hijack this thread entirely - I use the expensive LSD oil from Mercedes that seems to have a part number related to cars in the 90s and newer.   The guys at Mercedes told me its the same stuff that they used in the older cars "but not to worry, they had never seen a Pagoda with a LSD so just to use the regular gear oil".  And they want to work on my car??

Benz Dr. - you note that there is noise coming from your rear end.    Mine too - and it doesn't get louder or change if I go around corners or swerve from side to side.   I was thinking bearings (so I bought mine from Mercedes) but before I do that swap could the low level growling that I hear be normal and just be the LSD doing its thing?  I only hear it at low speeds but it is more pronounced when I go up a steep hill. 

[kampala]

The Mercedes specs for Limited Slip Differential states to use an oil that meets their spec number 235.7

https://bevo.mercedes-benz.com/bevolisten/231.1_en.html

The part number advised by Classic Center (A 001-989-33-03-12) meets 235.7 

It is Castrol CASTROL SYNTRAX LIMITED SLIP 75W-140. Or you use mineral Oil CASTROL AXLE Z LIMITED SLIP 90, this was in the axle when the car was new.

The  CASTROL SYNTRAX LIMITED SLIP 75W-140 meets Mercedes spec 235.61 which is called out for AMG. 

[stickandrudderman]

I've used Veedol LS90 for the last 36 years.

[Benz Dr.]

Not to hijack this thread entirely - I use the expensive LSD oil from Mercedes that seems to have a part number related to cars in the 90s and newer.   The guys at Mercedes told me its the same stuff that they used in the older cars "but not to worry, they had never seen a Pagoda with a LSD so just to use the regular gear oil".  And they want to work on my car??

Benz Dr. - you note that there is noise coming from your rear end.    Mine too - and it doesn't get louder or change if I go around corners or swerve from side to side.   I was thinking bearings (so I bought mine from Mercedes) but before I do that swap could the low level growling that I hear be normal and just be the LSD doing its thing?  I only hear it at low speeds but it is more pronounced when I go up a steep hill. 

The growling noise you hear is the clutch plates slipping. I only hear mine when making sharp turns at fairly low speeds. I've never heard mine making noise while going up any steep hills but then we don't have any steep hills around here. Your clutch plates could be getting a bit worn.