Red Line 75W90, 3.6k mi OCI, 153k mi, Cadillac CTS-V

[Emperors6]

Previous UOA is here. VOA is here. UOA history for this vehicle is available with this search: https://bobistheoilguy.com/forums/s...c[title_only]=1&c[users]=Emperors6&o=date&g=1.

Note from oil analyst: "Elevated levels of Iron and Copper. For the duty cycle on this differential, you might want to consider a 75W-140 or 80W-140 gear oil."

Made a wear chart (vertical axis is logarithmic, horizontal is days since first OCI). I'm trying to figure out why Iron and Copper have been spiking since the last few years. I switched to RL 75W-110 to see if that significantly helped. For the upcoming fill, I changed to HPL Differential Life 75W-90 Cold Climate. I plan to change the differential gear oil at the time as the engine oil since it takes less than 2 quarts. I'll do that for a few OCIs with the HPL and see how it trends.

 

[fantastic]

Did you end up going to a 140? Dana wants a 75-90 in my F350 rear axle but when I changed the fluid seen quite a bit of metal on the magnet & am happy to of went to a 75-140. I don't know anything about axles & their wear levels but it's always interesting to see. It seams your at least keeping track of your changes which is wise. What are you long term plans?

 

[SubieRubyRoo]

Did you end up going to a 140? Dana wants a 75-90 in my F350 rear axle but when I changed the fluid seen quite a bit of metal on the magnet & am happy to of went to a 75-140. I don't know anything about axles & their wear levels but it's always interesting to see. It seams your at least keeping track of your changes which is wise. What are you long term plans?

Run that sucker til it looks like this:

 

[Emperors6]

I haven't tried a 75w-140 yet since the differential doesn't get that hot, at least from the outside of the case with the temperature sensing adhesive I tried. If things don't improve in a few OCIs (I'm doing some short runs), I'll try that next. My longer term plans is to shorten the OCI to the same length as the engine oil. However, if it fails it fails, it's already over 153k miles/10 years. So, if it fails soon, the next one will hopefully last me that long, and by then the car's frame will be 20 years old and I'm guessing the frame will be condemned due to rust. I do spend 3-4 hours every year spraying the frame wherever I can, including inside the frame, so everything underneath is covered in a nice black and thick layer of dirt with oil mixture to provide a barrier to moisture and salt. However, it is my daily and winter beater.

 

[fantastic]

Sounds like a good plan. Those are awesome cars.

 

[Emperors6]

Too awesome not to obsess over maintenance.