190E 16 valve LSD differential gear oil question
 

I am almost ready to install a LSD diff from a 16 valve into my 190. MB recommends their own gear oil but no one seems to know the weight of the oil, the bottle does not say (just says GL-5).

Of course I don't really want to run the OE MB LSD gear oil, I would prefer to use Mobil 1 synthetic, which is a 75w90 weight and is listed as exceeding GL-5 specifications and also is listed as being compatible with LSD.

Anyone have any comments?

Mineral oil based GL-5s are typically 80W-90 and synthetics are typically 75W-90. Either is okay. The only other somewhat common GL-5 is 140 and you DO NOT want that.

The most important issue with a limited slip diff. is to be sure that the gear oil you use either has the friction modifier additive or if not, you must buy a the friction modifier and add it.

I've been through this many times with GM limited slips units that have the same clutch pack type (or cone type) limited slip and I ONLY use GM oil and additive because I know it works.

I've heard that Redline 75W-90 gear oil works okay in limited slips and Redline says it already has the additive, but most commercial GL-5s don't. Redline also has a 75W-90NS (non-slip) product for open diffs.

If you want to use oil you buy from an M-B dealer you should determine whether or not the product you use has has the friction modifier for limited slips or if it must be added.

If the M-B product is specific to the 16V and 560SEL then is might already have the additive as these were the only two U.S. models from that era that had a limited slip.

Duke

The limited slip in MB's use a clutch type differential lock-up system. So any QUALITY limited slip fluid will work. The factory fluid is expensive & I always use Redline products in my racecar & 16V street car.

Ok, sounds good. I have a quart of Mobil 1 synthetic, it says it meets/exceeds GL-5 specs and there is also a comment about it eliminating chatter associated with LSD diffs.

What would be the logical conclusion about the Mobile 1 then? There is no specific mention about a "lsd additive"

I suggest you go to the Exxon-Mobil Web site and see if you can find more specific product info. If not, e-mail them with a specific question.

Duke

I guess this paragraph from Mobil's web site answers my question about the LSD additive.

Features & Benefits
Mobil 1 Synthetic Gear Lubricant LS 75W-90 combines wax-free synthesized hydrocarbon base oils and a specially designed extreme-pressure, limited-slip, sulfur-phosphorous additive system to provide a significantly higher level of performance in rear axles and differentials versus conventional fluids. Greater film strength at higher operating temperatures, reduced fluid friction and low-temperature application down to -50ºC provides significant advantages versus conventional mineral oil formulations. It reduces wear and spalling under the high speed, high torque and high horsepower conditions in competitive racing and high performance automobiles. This unique, high technology final drive gear lubricant has demonstrated outstanding performance including; fuel economy, extended drain, long-term friction retention, low-temperature capability and improved differential/axle durability and cleanliness. Key features and benefits include: