Hey Gang,

Long story short, through another concern I shared on another thread it was suggested I have the dealer look at the fluid level in my pumpkin. I took my truck in for its first oil change (3k) on Monday and added the pumpkin fluid level as a concern on the work order. Lo and behold they needed to put a quart of fluid in my pumpkin.

I had pressed the service advisor if I had done any damage to the rear end while driving it around underfilled; he stated confidently that it was just low, but not worrisome. He advised if they need to add 2 quarts or more it might be a different story.

For the first time on my way into work, mind you its 20 degrees outside, my lie-o-meter pushed over 16mpg. I'd normally need to drive a full tank on a highway in warmer weather to see it get there. I do all my mileage calcs by hand so I take the lie-o-meter with a grain of salt, but still. I've never seen it bounce over 16 on a commute into work.

I'll see how my tank averages change with time or if this is a fluke. I'm glad some of you guys advise I have that checked; I just hope my service advisor was giving me good information with regards to my pumpkin being ok. It was all unladen, non-towing, mostly highway driving if that matters.

 

Most likely the rear end is fine, I am assuming you have the 11.6" rear end? I don't know the capacities of that off hand but I would venture to say your fine. Maybe do a dump and refill on the earlier side to be safe. Isn't that hard to do other than the smell. Fortunately the 11.6 has a gasket now so changes are faster than the RTV sealed axles of the past.

 

I don't know what I've got back there aside from the 3.73 e-locker. I THINK it's a Sterling? I'll fully admit I'm out of my water when it comes to rear-end tech talk.

 

When I got my truck home I found both diffs and the transfer case were a bit low. I added almost a quart of gear oil to the rear diff and about 1/2 quart to the front diff, and 1/2 quart of ATF LV to the transfer case. So I’d advise anyone to at least check theirs.

 

I thought it was mentioned that the "advertised" capacity, once filled with that amount, may not reach the fill hole.
I just did my 11.6 and would love to tell you I put in the exact amount and it lined right up with the fill hole.

but this is the fill hole.



and I made a huge mess and leaked a bunch out until I figured a decent method that got more fluid in the diff vs on the ground
(in a timely manner, using 1 qt,. correct Motocraft fluid bottles).

I ended up filling to fill hole, letting drain until it was level, like every other diff I've done for 40 years.
(and yes, I tried rotating diff 360 degrees, to see if there was a spot that "cleared" the fill hole, nogo on that)

 

About 1/4" to 3/8" below the fill hole is correct fill level.
Was always told if you can stick your pinky finger in the hole and touch the fluid, you're good to go.

 

Well Ford hasn't made it easy since some trucks have the old 10.5" sterling (like my 2019), some have the Dana M275 and now the "super sterling" 11.6" how shown up. Gets very confusing very quickly.

These little pumps really help with x-case and diff fluid fills, and now 10R140 fills...

 

Whoever decided to start putting diff fluid in those fluid bags needs a big ole pat on the back. I swapped my diff cover with a Banks cover. That one has drain and fill ports along with a sight glass for piece of mind.