Rear Axle Oil-Worth Changing?

[Strife]

I've been considering changing my rear axle oil this weekend (no tricky limited-slip oil needed, I have a "normal" unit). Is this worth doing? Is this a case of don't fix it if it's not broke? I'm considering doing it simply because the oil is going on 20 years old. Certainly, it must have broken down a bit during those 20 years, and/or a few metal shavings are suspended in there somewhere. I have the seals, manuals, and the tools needed to get the drain/inspection plugs off (hopefully).

[230/8]

It never hurts to change lube oils. Recommend that you first verify the filler plug can be removed. It stinks (along with the gear oil!) when you drain the old oil and then discover you cannot get the fill plug out to refill...

Cheers,

230/8

[Otto w. Coers]

Every new-to-me vehicle gets ALL new fluids. The rear end should be drained and refilled with the spec'd oil AND additive. If the oil that comes out is really bad you can lift the rear end off the ground, fill it with diesel and let it run for a while to wash the grime out, then drain and refill it with spec oil. Don't drive it with the diesel in the differential.
Otto

[dmorrison]

Originally Posted by Strife

I've been considering changing my rear axle oil this weekend (no tricky limited-slip oil needed, I have a "normal" unit). Is this worth doing? Is this a case of don't fix it if it's not broke? I'm considering doing it simply because the oil is going on 20 years old. Certainly, it must have broken down a bit during those 20 years, and/or a few metal shavings are suspended in there somewhere. I have the seals, manuals, and the tools needed to get the drain/inspection plugs off (hopefully).

Just to make sure your saying what I'm hearing!!!!!!!!!!!!


Model 107.048 560SL.

The 86 DOES have a limited slip differential.Unless you have "modified the car"

Dave

[Strife]

Originally Posted by dmorrison

Just to make sure your saying what I'm hearing!!!!!!!!!!!!


Model 107.048 560SL.

The 86 DOES have a limited slip differential.Unless you have "modified the car"

Dave

I have the old MB manual on CD, and it CLAIMS that units that have limited-slip have a tag on the bottom of the axle indicating this. Mine doesn't, but perhaps they stopped doing this (the manual I have is mostly on pre-86 with 560sl "addenda")?

[Roncallo]

The one bad thing about tags is that they are often removed. I'm not aware of any 560SL's without limited slip. If your car has milage on it the clutches are probably worn and if you jack up one wheel you will probably be able to spin it like a standard differential. That doesent mean that the limited slip feature isnt working at all. It will need a partial torque load on one wheel to engade the worn clutches. With new clutches there is a preload on the clutches that gives you some traction on glare ice.

Since I dont know what the clutches are made of and since MB does not approve of any other gear lube. I use only MB gearlube for this car. It is $62.00 for 2 qt. but a cheap insurance policy in that I know am putting the right stuff in.

John Roncallo

[Strife]

The wonderful dealer in my area claimed:

1. The car had no limited slip - no tag, no limited slip

2. They only get that oil in bulk and had no means of ordering it.

This is why my car can't be serviced there, and why I'd be scared to death to buy a new MB.

[speedy72t]

That's why I'm scared to death to buy ANY new car. Cars are getting to be like computers. some engineer somewhere knows what actually went into the box but no one else does.

[Steve Gutman]

Changing the rear end fluid isn't a bad job and adding the limited slip fluid won't hurt if it doesn't have it. I used a Mobile product for limited slip. I have no tag but the wheels turn opposite each other. Changing this fluid in my Benz after 20 years yielded the stinkiest fluid I ever smelled. My wife even made a comment. I changed it in my BMW but it smelled fine. I think it was already changed in the BMW.

Regarding buying a new car, I would only do it if I intend to stop all my DIY work. The new cars are "black boxes" and lots of the repairs are designed to make you buy a new car. Look at exhaust, cats and sensors. At a mechanic's shop I saw a rusted out exhaust off a newer SUV and it was $2500 with no way to repair. A mechanic friend told me when he went to work at his first job (GM Dealer) that his job is to sell new cars. Find so much repair that the customer wants to buy a new one rather than spend so much to repair the old one. Most cars today, even super expensive ones are disposable. Can you imagine an engine rebuild on any AMG Motor?

[callen]

Back when HEI came out on cars in 74 people were aphrehensive...when computers were added in 1981 people were aphrehensive....same with ABS and everything else that's new.....there will be a way for a DIY to make it even with newer cars...they still have fuel pumps, tie rods, water pumps, coils......and suspensions haven't changed much....sooo lets not get to "sky is falling" with these newer cars.......course I cross my fingers on my new (to me 99) that I'll be able to do it all myself... I'm sure as hell gonna try.

[DavidSoine]

Yes change the fluid. I could not believe the putrid sludge that drained out of the diff on our car!

Dave
87 560sl

[jkford13]

I was lazy 3 months ago and had my oil changed at an EZLube. While there, the tech pointed out that my differential fluid needed changed. It was $50 or so, and at the time he gave me some rationale why it was a good idea. (don't remember that rationale now)

However, after reading several posts, it sounds like refreshing this fluid on an almost 25 year old car is a good idea. The problem is, about 3 weeks after the change, I have started noticing whining during deceleration. I believe it is there on accel also, but masked by engine noise.

My friend who is a car guy (rebuilt his Cleveland small block on his late 60's stang) and a cynic said they probably forgot to replace the fluid.

My 380SL has been parked for 2 weeks while I do a timing chain replacement and some other repairs. Before I drive her again, i'd like to verify that there is fluid. Is there anyway for me to check this without draining it?

Thanks,
Justin

[DavidSoine]

The car should be level - remove the fill plug and see if there is fluid up to the threads.

Good luck,

Dave
87 560SL

[Engr693]

Originally Posted by Strife

...- no tag, no limited slip....

Not true...my 73 450SL has limited slip but the tag has long been lost.
.
LSD shows up as an option on your data card (if it is an option for that year).
.
It was an option for my '73.

[Strife]

BTW, I found out that "stinky" fluid here is not any indication of a problem. There is a lot of sulphur in this oil (on purpose!), because apparently sulphur has good lubricating properties, is cheap, and, being an element, doesn't "break down".