Diff oil questions on the 124

[BillyW124]

Hello Chaps,

Service is due soon and am wondering if its worth having the diff oil changed?

i figure this is a 'once in a blue moon' change for which probably hasnt never been done?

Obviously first i will have to check the level and fill accordingly if low.

Questions:

• Is there a dipstick of somesort?

• Is there any running advantages of flushing the old oil out and putting in new fresh oil?

• What type of oil may this be?

• Am i able to even drain the old oil out?

Help appreciated.

 

[BlackC55]

No dipstick.

The top level is up to the fill bung.

Drain by undoing the lowest bung. Fill using the highest bung until it runs out.

80W90 oil

 

[BillyW124]

Cheers olly,

 

[BillyW124]

is it worth doing then?

 

[BlackC55]

It all depends on mileage. Any more than 50k then yes.

 

[BillyW124]

right well my car has around 102,500 on the clock so from that assumption it would be good to change.

I should mention that my diff is 'standard' no LSD etc.

 

[Niks]

Mine defo needs doing then!

 

[BillyW124]

i'm pretty sure though there would be a lot of 124's with much higher milage out there with the same oil in it perhaps?

 

[grober]

If you are going to perform a complete "drain n change" as opposed to a top-up ALWAYS check you can undo the level /fill plug before opening the drain plug. You will need some form of syringe or squeezable container to fill the diff from below. Standard diff oil as Olly says except if you have an ASD diff which runs on hydraulic fluid from a reservoir in the engine compartment.

 

[BillyW124]

If you are going to perform a complete "drain n change" as opposed to a top-up ALWAYS check you can undo the level /fill plug before opening the drain plug.

gosh, that heart sinking moment if i took off the drain plug and the filler was 100% jammed!

 

[balge]

Definitely got rid of a bit of whine from the back end after doing mine (200 000 on it). Oil looked ok-ish, a bit dark and slightly smelly.
Just get the oil in a bottle with a 'straw' on it, you can easily squeeze the oil in. Think it takes 1.1 litres...if you fill to the edge of the drain hole

cheers

 

[BillyW124]

is this Castrol oil ok?

ive been doing a bit of research and they say the recomended is a GL-5? if im not mistaken 80W90 is a GL-5?

Halfords | Castrol Differential EPX 80W/90 1 Litre

 

[trapperjohn]

Just over 1000 miles ago my diff oil was changed. Car just coming up to 200.000 miles.

I bought Carlube EP75w90 Hypoid Gear Oil for the job. No issues, no worries, no graunching and certainly nice and quiet back there.

Why Carlube? It was all the Autofactor had at the time. £7.99 per litre.

 

[grober]

The recommended MB approval is 235.0 (SAE 90) met by this for example:-

Fuchs TITAN Gear Hyp 90 Hypoid Gear Oil GL5 80w-90 which seems to have a very similar spec to the Castrol diff oil you listed so should be fine.

http://www.eternaplc.com/downloads/Castrol EPX_Gear_Oils.pdf

 

[BillyW124]

Thanks guys !

 

[grober]

Just over 1000 miles ago my diff oil was changed. Car just coming up to 200.000 miles.

I bought Carlube EP75w90 Hypoid Gear Oil for the job. No issues, no worries, no graunching and certainly nice and quiet back there.

Why Carlube? It was all the Autofactor had at the time. £7.99 per litre.

If we were splitting hairs [ when do we ever?] I would venture that the Carlube EP75W90 is more of a "gearbox oil" than a "diff oil" per se. MB seem to like a slightly heavier dedicated oil for their diffs= EP90
Certainly not listed under MB 235 Mercedes-Benz Betriebsstoff-Vorschriften: Motoröl, Getriebeöl, ATF, Kühlmittel, Bremsflüssigkeiten

 

[BillyW124]

If you are going to perform a complete "drain n change" as opposed to a top-up ALWAYS check you can undo the level /fill plug before opening the drain plug. You will need some form of syringe or squeezable container to fill the diff from below. Standard diff oil as Olly says except if you have an ASD diff which runs on hydraulic fluid from a reservoir in the engine compartment.

Would a litre bottle be enough for it to fill to the brim?

 

[grober]

Would a litre bottle be enough for it to fill to the brim?

If memory serves correct the quoted capacity is 1.3 litres but since some oil is normally left in there unless you let it drain overnight, you would probably get away with a litre. If the oil you drain off is OK then you could filter it and use a little for a final top up??- after all there is going to be some residual oil in there anyway. It will smell bad due to its chemical composition. Or you could just buy another bottle of course.

An exception to this would be if the diff was leaking badly - gauged from how much you drain off- in which case a top up right to the brim and regular checks/topups would be desirable.

 

[BillyW124]

I'll just get two bottles and take it from there really, Obviously the rest spare can be used as top up if nessasary in the future. the oil cost isnt a lot any how.

Another viable question (sorry!) Not sure what the set up is like under there for the diff, but are the drain and filler plugs like rubber bungs or similar?

If so might be an idea to get fresh new rubbers or bungs on these points?

 

[grober]

I'll just get two bottles and take it from there really, Obviously the rest spare can be used as top up if nessasary in the future. the oil cost isnt a lot any how.

Another viable question (sorry!) Not sure what the set up is like under there for the diff, but are the drain and filler plugs like rubber bungs or similar?

If so might be an idea to get fresh new rubbers or bungs on these points?

They are threaded reuseable substantial steel plugs[ no seals required] with a large socket for an allen key 14mm from memory. You can buy adapters for socket sets Halfords | Halfords Hexagon Drain Plug Key 14mm 3/8" or make one up BMW E46 Differential Info - 14mm Socket for cheap