Uknown oil/mile, 118k on 97 Chevy C3500

[TXHunter]

No history on this truck, replaced the rear diff fluid with Amsoil 75w-140 (SVO). This truck shows to have a Dana 11RG rear diff. This one is used as a cattle feed truck, has a replacement bed with cattle hopper installed. Only leaves the ranch to pickup feed and refill with gas. They are putting about 1k a year on the truck.

 

[Texan4Life]

HOLY HEMATITE BATMAN!

 

[Samilcar]

That used oil was 0.3% iron. Wow.

 

[JGW]

Originally Posted By: Texan4Life
HOLY HEMATITE BATMAN!



+1

 

[SuperDave456]

Probably been in there since '97.

Could it be condensation build up in the differential due to lack of use? Or just not getting up to temp?
Makes me think that there is something else going on with your differential other than just worn out gear oil. Although I have been wrong before.

 

[Rob_Roy]

That oil was certainly overdue for a change. If the differential isn't making any strange noise or vibration, it is certainly possible that the FE just accumulated over the years and made the oil slightly abrasive.

Considering the axle is heavily loaded and used at slow speed, I think a sticky SAE 90 would be a good choice.

 

[Jim Allen]

My books show this would be a Dana 80 DRW axle. They are strong and reliable but if they have a weakness, it will be the ring gear side carrier bearing. If the oil has never been changed in all those miles and all that work, it doesn't surprise me to see those numbers. What usually kills Dana 80s is long periods at high loads, high speeds and high oil temps. Short, low speed work, even if over GAWR, don't usually hurt them much and that sounds like the life this truck has lived. I'd just run it with 75W140 you installed but pay attention.