If the drain plug won't come out just remove the diff cover. You'll just need to support the diff with a floor jack or something because you will need to remove the rear mount. No big thing.

After I picked up my 300K mi 300D I found the differential low by ~40% on lube oil. I topped it off with standard 75-90 oil.

Q - Does anyone think I would benefit by making an initial hot-oil change to Mobile-1 and then later changing again... whill this help to reduce the what I will call the "sounds of looseness" I hear from the rear end?
Sam // Novato, CA

MB service CD tells me to drain differential oil only when the rear axle is at operating temperature.

How long should I drive the car to bring the differential to operating temperature?


If I go to an instant oil change place, do they tighten the filler and drain plugs to correct specification (50 Nm in my case), and do they do clean job (not putting dirt outside the differential around the filler hole into the differential)?
I am trying to avoid paying for the labour cost to drive my car to bring the differential to operating temperature.

__________________
1992 300D 2.5 turbo diesel. 319 k miles.
124.128 chassis, 602.962 engine, 722.418 tranny.

I wouldn't you could burn yourself. Its gear oil, as long as its warm out it will drain just fine.

__________________
1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

but, let's get real here.........how hot does a rear-end get? Most heat back there you'll find comes as radiant heat from the exhaust.....heavy around town driving will probably warm it faster than 55mph cruising........

just my theory anyway..........

__________________
-Matt

EPA Section 609 Certified MVAC Technician
-----------------
Oil Burner Kartel Member #10

Ahh the smell of Diesel Fuel, it's like coffee in the morning!

My Car:

1982 300SD Turbo Diesel (231,500 miles!) RIP

1984 300SD Turbo Diesel Custom (235,500 mi on driveline.) - On Road!!

www.icsrepair.com

Unless you have a lift, getting under a hot car is not going to be fun. Plus I wouldn't want to find out, because no matter how carefull you are the old fluid is going to get on your arms.

90% of these cars probably drive into the junk yard on the original fluid put in back in Germany. So changing it hot vs cold, come on.

__________________
1999 SL500
1969 280SE
2023 Ram 1500
2007 Tiara 3200

Iffy Loob? Never!@
I let mine drain overnight (all weekend if possible) its amazing how slow that stuff comes out by the time its finished it will be cold regardless of the temp when you start

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!

I used a regular L-shaped Allen wrench (couldn't find a 14mm Allen socket when I went shopping) but I also got an 18 inch steel pipe (half inch fits perfectly) to give me some leverage. The first time on my '85, the fill plug wouldn't come out so I removed the cover, as was mentioned above. Once I had the cover on the bench, I warmed it gently with a torch and the plug came right out.

I now carry the Allen wrench in the spare tire well, just in case I have to do something on the road. The pipe fits alongside the jack.

Oil always drains better when it's warm. I wouldn't drive the car just to warm up the oil but I would make plans to change the oil just after a drive that was done for some other reason. For example, I changed the engine oil today as soon as I returned from the San Jose area (100 miles at mostly freeway speeds; the engine was definitely "warm").

Jeremy

__________________

"Buster" in the '95

Our all-Diesel family
1996 E300D (W210) . .338,000 miles Wife's car
2005 E320 CDI . . 113,000 miles My car
Santa Rosa population 176,762 (2022)
Total. . . . . . . . . . . . 627,762
"Oh lord won't you buy me a Mercedes Benz."
-- Janis Joplin, October 1, 1970

Changed the rear diff. fluid in my '85 300TD (wagon) today. As soon as I removed the fill plug I smelled burnt transmission fluid. I removed the drain plug and sure enough its red with a brownish tint. Once the fluid stopped draining I put my finger inside the diff. to see if any was left inside. Some of this red fluid has gelled like jello and put a coating on the bottom inside of the diff. I replaced with Mobil 1 synthetic.

Is it correct to use transmission fluid in the rear diff?

Or is this old fluid/gel possibly something other than trans. fluid?

__________________
JWJ
1983 MB 300D - > 430,000 miles - Deep Blue - Bilstein Comforts - 0-60 in 24 seconds - 27MPG
1985 MB 300TD (wagon) - > 275,000 miles - Manila Beige - Thule rack - 0-60 in 18 seconds - 22 - 25MPG
Biodiesel, Mobil Delvac 1, and Viton fuel lines!

Not on your life.

Gear lube will have a unique smell, not at all like ATF or motor oil. And it won't be red.

__________________
2009 VW TDI Jetta Sportwagon 172k miles (rear-ended harder than Elton John on 8/4/13. Total loss)

1991 Volvo 240 142k miles (T-boned by a stop sign runner. Total loss)

I changed the diff fluid in the wagon a while back, and it was the foulest smelling stuff I have ever drained from a vehicle. It didn't look that bad either to tell the truth, but it smelled like Fido's arse.......
Went with Royal Purple for the diff fluid. Couldn't afford it for the tranny.....

__________________
Jimmy L.
'05 Acura TL 6MT
2001 ML430 My Spare

Gone:
'95 E300 188K "Batmobile" Texas Unfriendly Black
'85 300TD 235K "The Wagon" Texas Friendly White
'80 240D 154K "China" Scar engine installed
'81 300TD 240K "Smash"
'80 240D 230K "The Squash"
'81 240D 293K"Scar" Rear ended harder than Elton John

JimmyL - sounds like you and Fido are really close.

Len

Could somebody answer a question for me?

How difficult/easy is it to check the breather valve on the diff of a W210?

I want to change the fluid this week, but would appreciate comment on access to the breather to see if its clear?

Not sure about W210, but suspect differential not much different than say W124 differentials. There is no breather valve, but rather just an opening high up on the backside of the differential case.

Crawl under there and have a look.

Steve

Thanks, I should be doing the change tommorrow, but this page would seem to suggest there is a breather valve:

http://www.detali.ru/cat/oem_mb2.asp?TP=1&F=210225&M=606%2E962&GA=722%2E608&CT=F&cat=45Q&SID=35&SGR=015&SGN=01

Part 152