Mercedes-Benz Forum banner

1 - 15 of 15 Posts

·
Registered
Joined
·
60 Posts
Discussion Starter #1
It's been a busy few months, with new shock absorbers all round, new brake calipers all round, steering damper, rear anti roll bar links etc etc etc

Time to change the rear diff oil as i guess it's not been done for years.

Has anyone got a diagram of the drain plug and fill plug locations? and what oils is specified?
 

·
Registered
Joined
·
2,279 Posts
As specified in your manual, you want 90-weight non-synth gear oil. The drain is on the bottom, the fill is on the top off to one side. If your drain looks clean with no sign of leakage, try removing only the fill and siphoning it out. It is yucky stinky high-sulphur goo but steel loves it.
 

·
Registered
Joined
·
60 Posts
Discussion Starter #3
As specified in your manual, you want 90-weight non-synth gear oil. The drain is on the bottom, the fill is on the top off to one side. If your drain looks clean with no sign of leakage, try removing only the fill and siphoning it out. It is yucky stinky high-sulphur goo but steel loves it.
Thanks

I checked with Mercedes and they said standard SAE 80/90 GL5 gear oil.

Thanks for your help - much appreciated :thumbsup:
 

·
It Is What It Is, Dude
Joined
·
22,839 Posts
.


Loosen the fill plug before you drain the diff. Nothing worse than pulling the drain and finding out you CAN'T get the fill plug out.
 

·
Registered
Joined
·
6,147 Posts
Lets see if I can confuse the issue.

Does the 300SL have a limited slip differential like the 560SL?

If so, I believe it takes a different oil or at least an additive.

If not.... Never Mind. :)
 

·
Registered
Joined
·
60 Posts
Discussion Starter #7
Lets see if I can confuse the issue.

Does the 300SL have a limited slip differential like the 560SL?

If so, I believe it takes a different oil or at least an additive.

If not.... Never Mind. :)
No LSD on Euro spec 300SL apparently
 

·
Registered
Joined
·
509 Posts
I too have heard the warning about the bottom and side plug issues, and the possibility of stuck of damaged plugs/threads. I'd definitely heed the advice.
_
 

·
Outstanding Contributor , Bob's Your Uncle!
Joined
·
29,105 Posts
I too have heard the warning about the bottom and side plug issues, and the possibility of stuck of damaged plugs/threads. I'd definitely heed the advice.
_
I haven't heard anyone with a Benz have the problem but it is Mechanics 101.

Don't drain until you know you can fill.

In aviation: don't remove a part until the new one is in your hand.
 

·
Registered
Joined
·
3,198 Posts
It is good practice to take the fill plug off first. Did I ever mention changing the manual transmission fluid in my pickup? Some ape brained person put the fill plug on so tight it stripped the fill plug when I tried to remove it. It took me a few months of thinking before I got under the car and dremeled off a piece of the fill so I could get a pair of vice grips on the damned thing. A trick is to find the vice grips with the little allen on the end so you can really lock the teeth down. It took super tightened vice grip and a 3 foot breaker to get the fill plug off. It probably only needed 10-20ft/lb of torque to seal the plug.
 

·
Registered
Joined
·
60 Posts
Discussion Starter #12
Cheers guys,

Took your advice and freed off fill plug 1st:thumbsup:

Drain plug was ok as well but, needed a breaker bar to loosen.

Quick question though. The manual says 1.0 litre of oil for 300SL diff however, a litre has gone in but it's not coming out of the fill plug?

I assume the fill plug is also the oil level plug as well?
 

·
Registered
Joined
·
973 Posts
I assume the fill plug is also the oil level plug as well?
Yes. But if you've jacked up the rear of the car higher than the front, added hypoid oil until it runs out, and THEN replaced the plug, the level will be too high at the car's operating height.

Lower the car completely to do the final fill. Or, as I do, remove the filler plug a second time and let the excess oil run out. When it stops, you'll have added the perfect amount of gear oil--uh, assuming your garage floor is flat, that is.

Good road,
 

·
Outstanding Contributor , Bob's Your Uncle!
Joined
·
29,105 Posts
Yes. But if you've jacked up the rear of the car higher than the front, added hypoid oil until it runs out, and THEN replaced the plug, the level will be too high at the car's operating height.

Lower the car completely to do the final fill. Or, as I do, remove the filler plug a second time and let the excess oil run out. When it stops, you'll have added the perfect amount of gear oil--uh, assuming your garage floor is flat, that is.

Good road,
+1


And make sure the vent is clear and not covered in gunk.
 

·
Registered
Joined
·
60 Posts
Discussion Starter #15
Yes. But if you've jacked up the rear of the car higher than the front, added hypoid oil until it runs out, and THEN replaced the plug, the level will be too high at the car's operating height.

Lower the car completely to do the final fill. Or, as I do, remove the filler plug a second time and let the excess oil run out. When it stops, you'll have added the perfect amount of gear oil--uh, assuming your garage floor is flat, that is.

Good road,
Cheers guys:thumbsup:

Old diff oil was very old at a guess - more black than gold. So good job it was changed - and at very low cost:thumbsup:
 
1 - 15 of 15 Posts
Top