CAT D6C lubricant question

i think your suggestions are correct...except for the Final Drives, i was told 80-90W Gear oil or something similar....you might be OK with TDTO 50, not sure

my 941b calls for 50 weight oil in the final drives so i think you will be ok--50 wt motor oil is very close in viscosity to 80-90 wt gear oil

50W for finals is ok for colder and warm temps. 30W for engine oil or 15W-40 is ok. 10W Hyd. 30W transmission drive train for the trans/strg clutches.

I had a BAD result using 50# engine oil in final drives!! ruined a bull gear and a reduction gear, I have changed to synthetic 75-140 and in hot weather a synthetic 250 unlike mineral oil it will flow in cold weather in this day of expensive hard too find gears it’s darn cheap insurance!!!! 17a farmer

How were the bearings and gears before using 50W?

I had a BAD result using 50# engine oil in final drives!! ruined a bull gear and a reduction gear, I have changed to synthetic 75-140 and in hot weather a synthetic 250 unlike mineral oil it will flow in cold weather in this day of expensive hard too find gears it’s darn cheap insurance!!!! 17a farmer

was the oil zinc fortified. zinc fortified oils cant be used due the bull gear being made of bronze the zinc additive will attack it.
 

the easiest is contact the tech advice service of your chosen oil company they will give you a recommendation of what products in their range are suitable. some brands have different names for their products in other countries. even though the product is the same the name can be different they also change names too. chevron recently changed branding on all their heavy equipment oils and has grouped them under the delo brand name.

Never had problems with Cat 50W TDTO for years.