Changing the Differential Fluid

[255/85]

If thats the case what is the difference between 2.1 L and fill to spill??

At the widest part of the housing the 23mm difference could be a lot.

i think you're overthinking it. Telling people to fill until it runs out, isn't environmental conscious.

It's the lawyers' responsibility to specify "only to the the bottom edge of the fill opening" or 1/8" below, etc. No company in their right mind would instruct an end user to stuff it in there until it oozes out. We may be able to but, for the warranty period, I'll elect to follow the specs.

See where the oil level is in relation to the axle shafts are in the housing. They're likely keeping the oil level below the drive axle in the axle housing as the axle doesn't need to be in an oil bath. Looking at the diagram the fill plug is above the axles

What about the axle shaft seals? they'd need a little but constant lubrication. Kinda shoots my theory down.

 

[Zimm]

At the widest part of the housing the 23mm difference could be a lot.



It's the lawyers' responsibility to specify "only to the the bottom edge of the fill opening" or 1/8" below, etc. No company in their right mind would instruct an end user to stuff it in there until it oozes out. We may be able to but, for the warranty period, I'll elect to follow the specs.



What about the axle shaft seals? they'd need a little but constant lubrication. Kinda shoots my theory down.

The widest part of the housing up to the fill hole also happens to be where the mechanical bits occupying space flinging the fluid are located. A ford 10.25 is a much larger unit than this. it takes 3.5l per spec, but will not take more than 4l without spilling.

What would the lawyers be worried about?

I'm not telling you not to follow the specs, feel free. I'm saying any consternation about filling to the bung, is completely unwarranted and a special tool is kinda funny.

 

[255/85]

What would the lawyers be worried about?

The spilling, silly.

I'm not telling you not to follow the specs, feel free. I'm saying any consternation about filling to the bung, is completely unwarranted and a special tool is kinda funny.

In truth I'm not too worried but I also don't want to be the one that has fingers pointed in his direction when someone else's warranty is voided from following my advice. I have an aversion to authority... including my own.

It did only take roughly a half quart of extra fluid to overfill the D44 that I mentioned before. Not pretty but maybe not catastrophic.

 

[NQ94]

At the widest part of the housing the 23mm difference could be a lot.



It's the lawyers' responsibility to specify "only to the the bottom edge of the fill opening" or 1/8" below, etc. No company in their right mind would instruct an end user to stuff it in there until it oozes out. We may be able to but, for the warranty period, I'll elect to follow the specs.



What about the axle shaft seals? they'd need a little but constant lubrication. Kinda shoots my theory down.

There will be oil and splash in the axle tubes but the level below the axle shafts means that the axle isn't constantly churning in the oil. Similar to how truck axles lubricate wheel bearings. Most of the truck axles like Meritor and Dana manuals say fill to spill.

 

[Tom109]

No company in their right mind would instruct an end user to stuff it in there until it oozes out.

But that is how it has traditionally been done, and directly relevant for 50+ years.

 

[Dokatd]

But that is how it has traditionally been done, and directly relevant for 50+ years.

Different times my friend.