2017 Ford F53-Dana M80-Mobil 1 75W-140 20500 mi

Joined
Dec 22, 2006
Messages
544
Location
USA
First change - factory fill 75W-140
Code
Miles on unit  20500
Miles on lube  20500
Fe               112
Ch                 0
Ni                 1
Al                 2
Cu                 3
Pb                 0
Sn                 0
Cd                 0
Ag                 0
V                  0
Si                75
Na                 2
K                  1
Ti                 0
Mo                 5
Sb                 0
Mn                 1
Li                18
B                 30
Mg                 0
Ca                 9
Ba                 0
P               1064
Zn                15
Water            <.1
Visc 100c       24.8                     
This is a really good sample. The Fe is low for a first change. Si is likely from RTV sealant and the Li is probably wheel bearing grease. My plan is to sample through the fill plug every 10K miles and only change when the UOA dictates.
 

CT8

Joined
Oct 9, 2014
Messages
15,369
Location
Idaho
The costs of the uoa will be more that an every 50,000 to 100,000 mile oil change.
 

AITG

Thread starter
Joined
Dec 22, 2006
Messages
544
Location
USA
Originally Posted by CT8
The costs of the uoa will be more that an every 50,000 to 100,000 mile oil change.
Probably not. The removal, cleaning and reinstallation of the diff cover ... it's a PITA to do it. Plus, a new tube of gear oil resistant RTV each time? No thanks. Sampling is a lot easier. Keep in mind it took me two years to get 20k miles so I'm going to be sampling about once a year.
 
Last edited:

dnewton3

Staff member
Joined
May 14, 2007
Messages
9,368
Location
Indianapolis, IN
Once properly broken in (and presuming proper set up), a ring/pinion gear set can last a LONG time on moderate OCIs, even under heavy loads. Honestly you might consider scaling back on the UOAs, every 25-30k miles (every third year for your stated use) would be plenty. I agree that it would be easier to sample than drain/fill in this case. Use an inexpensive service like Wix; all you're really interested in is the major wear metals. Things like soot, TBN, etc are of no consequence here.
 

AITG

Thread starter
Joined
Dec 22, 2006
Messages
544
Location
USA
Originally Posted by dnewton3
Once properly broken in (and presuming proper set up), a ring/pinion gear set can last a LONG time on moderate OCIs, even under heavy loads. Honestly you might consider scaling back on the UOAs, every 25-30k miles (every third year for your stated use) would be plenty. I agree that it would be easier to sample than drain/fill in this case. Use an inexpensive service like Wix; all you're really interested in is the major wear metals. Things like soot, TBN, etc are of no consequence here.
Agreed. If the 10k sample looks good (and I expect it will) I'll stretch it out a ways. I've seen bigger Dana Spicer diffs go 500,000 miles on the factory fill without failures.
 

dnewton3

Staff member
Joined
May 14, 2007
Messages
9,368
Location
Indianapolis, IN
Yes - if the three following conditions are met, then diff failures are RARE - proper spec fluid is used (typically a fairly wide range of acceptable vis and base stocks will work) - proper ring gear and pinion set up for contact pattern, backlash, etc - proper light break-in before heavy use, to burnish the ring/pinion relationship If these are met, diffs are almost a fill and forget thing. And while that scares the Hades out of most BITOGers, the reality of anecdotal proof is in the scad-zillions of vehicles that see hundreds of thousands of miles of use and yet have few failures. I generally will run easy application use for about 1k miles on a new vehicle, change the diff fluids to flush out the break-in stuff, and then leave them be for at least 100k miles before even considering an OCI for heavy applications, and 150k miles for light applications. I might check the fluid levels every other year or so, but I don't change the gear lube until at least 100k miles has gone by. Case in point: my wife's former 2005 Grand Marquis with FoMoCo 8.8 diff. We got it used with 157k miles on it. I serviced all fluids which included the rear diff fluid; it surely looked to be the OEM fluid and there was no written or physical evidence that it had ever been changed in that first 157k miles. When my son and I pulled the diff cover, the fluid looked "iffy", but the ring/pinion and spider gears were perfect; the unit was still nice and tight with no abnormal wear anywhere and the contact pattern was text book perfect. After installing some dino 80w-90 and running the car another 110k miles, the car has recently been sold to a friend who continues to drive it daily. I told him he might want to change the fluid again since it's been 110k miles, and he said he might, if he gets around to it. But honestly, at some point, what is the point? Diffs don't get contamination as long as they are not submerged and the axle vents work well. Wear is normal on any mechanical device. The unit is so well burnished that overly anxious OCIs probably are not going to alter the seemingly limitless lifespan of the diff. It's a 4.6L equipped, 8.8" 2.73 geared vehicle that sees "normal" use. As a species, cockroaches are the only other thing I can think of which hope to live as long as those cars can run. For your F-53 Dana, I think you should take a UOA once another 10k miles has elapsed. Then you can probably push the next UOA out to 25k miles, then after 50k miles, and then at some point, you'll just either forget or get bored, realizing it's moot ...
 
Last edited:

4WD

$50 site donor 2022
Joined
Sep 21, 2010
Messages
19,625
Location
Texas
I had the rare of the rare … ring, pinion, spiders, pins, etc … all shot from viscosity break down. Dodge 1500 that did moderate towing (not that often) and mostly DD. Just out of warranty and lube had 32k (Pennzoil) … Strange wear … more liked rolled wear … no visible metal in the oil … oil clean, but very thin. And no heat checking even though it was past the harder surfaces. Not even galled. The $1300 rear end we put in had 20k more miles than the truck. Schaeffer went in that older pumpkin. I too do an early drain … but then around 50k per OCI …
 
Top