How many miles should I go before changing the rear diff fluid?

 

What is the year, make, model and number of miles on the OD? How long have you owned it? Doesthe log indicate it's ever been changed? Did you routinely change it when you bought the car, along with all of the other fluids?

 

I have a 78' 300D. It has 164k. I have owned it for 2 years and have put about 40k on it. I have not done it since I have owned it.

 

chances are the previous owner didnt do it either, unless it was maintained at a dealer for the life of the car and had every recommended maintenance done and no penny spared.

whether or not it is nessecary to change it is hard to say without seeing the car and checking the fluid condition, but i certainly wouldnt hurt the vehicle to do it, as long as its done right.

 

remember to clean every thing off to keep the grubby stuff out. secondly try the upper "fill" plug first. if you drain the contents you will have a fun night ahead of you if you can't remove the fill plug as well. my drain plug on my 76' 300d was froze up but that did not matter i got a large syringe, you can get them at auto parts stores or a medical supply house, and a length of tubing and just suctioned out the old contents and refilled with the suitable lubricant.

 

I read on dieselgiant about that and making sure to do the top first.

 

When buying a used car, unless I have a log that showswhen filters and fluids have been done, I automatically replace all fluids and filters, including the differential.That said,IMHO, your differential fluid change is long over due.

 

I agree on fluid changes. I just picked up a 79 240 with manual trans and looking for diff and gearbox fluid recommendations.

ATF for the gearbox?
Synthetic diff fluid, 75w-90 or 75w-110

I use amsoil synthetics in everything, any reason not to use them here?

Thank you! First post...

 

That comment about checking the Fluid levels after you buy a Car is extremely true. Many People do not even know the Differential Fluid/Oil needs to cecked let alone changes.
In the Old days when you got your Suspension,U-Joints and Chassie greased they also checked the Manual Transmission and Differential Oil levels.
Now the Suspension, Chassie and sometimes even the U-Joints cannot be re-greased so checking the Manual Trans and Differential Oil has fallen by the way side unless the Car Owner ask for them to be checked.

 

1992 300D 2.5 turbo; Automatic, standard differential

ATF: Liqui-Moly Top Tec 1100
Differential: Liqui-Moly 85W90 GL-5
Power Steering: Febi 08972

All meet the applicable MB specifications