Is 75w-90 ok? The oil I'm looking at is full synthetic will that do the job? Also I called the dealer and they said I need to add some sort of treatment is this true?

Here's the link of the oil I'm thinking it's castrol syntrax

http://www.castrol.com/liveassets/bp...0_B1278983.pdf

 

Please report how your looks and what condition it was after how many miles. Curious if I'd have to change my own in due time.

 

I used Mobil 1 75-90w full synthetic. It took about 1.5 qt.

Since we don't have a factory LSD, I cant see why they say you need an additive. However, it DOES need to be a Hypoid oil (Hi/Extreme-Pressure). That Castrol looks like it would fit the bill...

FWIW, The recommended fluids (Specs) are listed in the manual.

Disclaimer: I am not a certified mechanic, I just play one on tv... so, take my advise with a grain of salt.

 

I was told to use on mercedes diff oil or Mopar synthetic gear &axle lubricant(right off the bottle) yes it is about $50.00 a quart. and it says if used in a limited slip add mopar limited slip additive 04318060AB
jim

 

Thanks guys, we dont have Mobil 75w-90 in Australia for some weird reason, this Castrol seems to be the closest thing to the Mobil,

When I called the dealership I gave them my VIN and they said "yep you have a limited slip diff so it'l be $100 per ltr, (I'd need 2 bottles) and the special additive $40" so $240 is abit steep

PLUS it worries me that they think my car is a limited slip diff when it isn't, makes you think what they do to your car when you take it in


Hrmmm I wish I knew for sure if this Castrol is okay it's only $28 per ltr 2 bottles $60 and i'd have alittle bit left over.

side not my car has 80,000kms which I think is about 45,000 - 50,000 miles? but I've done abit of drag racing so it defiantly wont hurt to change it, especially since so many people are seeing diff failures

 

AMX1397, I don't doubt thats what the dealer told you. They are always going to say MB products only. It's a liability thing.

I also agree that there are some things that requires VERY specific lubrication... like auto transmissions due clutch properties, valves, etc... they have very precise friction additives.

But when it comes to a differential, unless it's an LSD (which we all know we dont have, except that dealer apparently LOL)... gears are gears.

Per the manual page 267 (SLK):
Recommended fluid - "Hypoid Gear Oil SAE 90 or 85W-90"

I researched this and read a LOT before I changed mine to Mobil 1 75W-90. Believe me there are a TON of threads that show most go to 75W-90. Everything I have read points to it being just as good if not better...

As usual, just my opinion.

FWIW, I'm a 37 yr old - 19 yr military aircraft mechanic that has worked on cars with my dad since I was old enough to hold tools. Not that that means a ton, just want to clarify that: 1) I'm not some 'kid' that believes everything on the web and 2) I am not a certified car mechanic... lol

Bottom line, do what you feel comfortable with... there are a LOT of opinions on the forums.

 

On this weblink I posted it says its good for SAE 90, so I hope I'll be fine I'll take the plunge and buy it.

From what I gather this Castrol Syntrax is nearly identical to the Mobil 75w-90

Thanks for the info Buggin!!!

 

Good luck finding SAE 90...was looking for two weeks, found it at napa but only in 5 gallon buckets...

 

This castrol is SAE 90, we have them in 1ltr bottles which is about 1.2quarts for $28 a bottle.

 

Owners Manual FWIW:

Only use synthetic SAE 75W-85 axle lubricant that meets MB 231.1.

Reduced axle durability may result if an unapproved product is used.


WOW, Redline sells it and it is only $12/qt. HERE

 

How about Redline MT-90?

 

How do you find out if it's mb approved? We have redline here but it's really expensive lol.

Are you allowed to take oil in your suitecase when travelling overseas? If so I'll stock up on my flight back to oz when I leave LA

 

Doubt it - when ordering oil (or similar) usually you can only choose ground shippping as it is "hazardous" material.

 

Red Line Synthetic Oil - Gear Oil for Differentials - 75W85 GL-5 Gear Oil

Not tried it - but interestingly enough, it claims to be compatible with the Crossfire - but makes no mention of MB??

 

From MB site:

Hypoid gear oils contain a high level of EP/AW additives (Extreme
Pressure/Antiwear) and a highly viscous base oil to prevent seizure
when the hypoid gears mesh (mixed and boundary friction
conditions) and to ensure a high degree of protection against
wear. The compatibility with radial shaft seals is regarded as
critical with such high concentrations of additives because the P/S
additive systems become thermally unstable at temperatures from
130 ∞C to 140 ∞C and this may lead to sludging of the hypoid oil.
The resultant deposits on the radial shaft seals then generally lead
to thermal overload and this in turn leads to leakage in this component.

The tooth engagement conditions of the hypoid gears result in a
high proportion of sliding and a low hydrodynamic proportion of
tooth engagement between the pinion and ring gear. Due to the
high tribological load compared to adhesive wear (seizure) and
pitting, the performance of hypoid gear oils must be particularly
high with respect to these types of wear. The formula of the oils is
therefore determined by a high concentration of EP/AW additives
and a highly viscous base oil. Alternative oils, e.g. engine oils,
cannot be used for these drive types. Proof of performance that
an oil fulfills the requirements of Daimler AG is provided by
internal tests. However, the hypoid gear oils must at least
correspond to the US military specification MIL-

L-2105 B/C/D and must be classed GL-5 in the quality grade according to API

(American Institute of Petroleum).