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When to change Front & Rear Diff and Transfer Case Fluids?

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14K views 9 replies 4 participants last post by  zthayer2.2  
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#1 ·
I have an 08 F-250 with 89k miles...probably 20% of that with trailer towing time on it. Being that it's 12 years old almost, I was looking through the manual for when I need to change out the front diff, rear diff, and transfer case fluids. Manual says to change rear diff fluid at 50k, 100k, and 150k (for DANA axles only), front diff fluid at 150k, and transfer case fluid at 150k miles.

Couple questions. How do I know if I have a DANA axle? I don't think I do since the owners manual makes it sound like DANA axles are on the F-350's and above only...and that I have a 10.5" axle? So if I don't have a DANA axle, then when should I be changing the rear diff fluid, 150k like the other fluids?

I saw this in the Special Information maintenance section: "Rear axles and power take-off (PTO) units containing synthetic lubricant and light duty trucks equipped with Ford-design axles are lubricated for life. These lubricants are not to be checked or changed unless a leak is suspected, service is required or the axle assembly has been submerged in water."

Are they really sealed for life units? I'm confused as crap! I attached the table of fluids I think I need from the manual.

Or should I just play it safe and change all 3 fluids at 90k or 100k miles since it tows occasionally? I haven't had any problems...maybe once every other month it will do a hard downshift when searching for the right gear.
 

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#2 ·
Change your rear dif fluid every 50k miles esp if you tow. Funny story and no lies... bought my 1999 f250 with 120k on the clock. The front dif oil looked/smelled brand new compared to the bottle. The rear dif was just a little discolored with 120k miles on it. the transfer case fluid was the worst though so im doing it every 50k like the rear dif etc.

The fact that you are even changing them once is more than what most truck owners do in the life of their vehicles.
 
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#3 ·
Thanks for the reply. So being that I very rarely use 4x4 (couple times in the winter is all), I probably don't need to change the front diff fluid right? I'll probably go ahead and order stuff for the rear diff and transfer case then. Do most peole just stick with the motorcraft brand of fluids that I listed out in the attached table?
 
#4 ·
Oil fluid and brands gets super heated but I rarely use motorcraft brand oils because of their price. I used Valvoline in numerous trucks with zero issues. I however will always buy motorcraft brand parts. It seems powerstrokes in particular go through generic brand sensors really quickly etc...

I found the rear dif in valvline at walmart and the front dif at napa etc.
 
#5 ·
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#6 ·
So buying fluids for the rear diff and transfer case right now. I'll probably go with Valvoline transfer case fluid...it says it's "recommended for Ford XL-12 specs", so should be just fine right? https://www.amazon.com/dp/B071VDQLV...B071VDQLVZ/?coliid=I8C7LLC6LOTQB&colid=1JWY71SHQ82FV&psc=1&ref_=lv_ov_lig_dp_it


The rear diff calls for SAE 75W-140 synthetic, so should I go with the Valvoline again? That will be much more expensive, but still cheaper than Motorcraft fluids. It says limited slip on the bottle, so it includes friction modifier. How do I know if I have a LS axle? https://www.amazon.com/Valvoline-75...JY/ref=sr_1_4?keywords=SAE+75W-140+synthetic&qid=1562768935&s=automotive&sr=1-4
 
#8 ·
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