Jim,
condemnation limits will vary somewhat from Manufacturer to Manufacturer. It would be fair to say though that the "limits" are quite universal in that the concentration is the deciding factor
These are limits from Eaton concerning truck diffs:
Viscosity at 100C - 20% +/- from new
TAN - increase of 2 over new lube
Phosphorus - 30% decrease from new
Iron - 1500ppm
Copper - 250ppm
Chromium - 10ppm
Silicon - 130ppm and other WMs are high
Sodium - 50ppm
Aluminium - 150ppm
Water 1% by volume
I used this lubricant (Mobil 75W-90) and Castrol's equivalent for many years in my Class 8 trucks. I did not carry out OCs at all before 1m kms (620k miles). Both the castrol and Mobil lubricants performed the same - both are great products!
This UOA was from one diff (front of tandem) and taken at 1.04m kms (646k miles) over four (4) years:
Iron - 569ppm
Aluminium - 8ppm
Chromium - 2ppm
Copper - 40ppm
Lead - 5ppm
Silicon - 138ppm
Sodium - 10ppm
Tin - 2ppm
TAN - 2.4
Water - 0.15%v
Viscosity - normal
Most diff lubricants are changed out far too soon - water may be an issue with some vehicles however if breathers are submerged from time to time! "Unpracticed" lubricant contamination can occer too for the unwary!!!
The 1m (620k miles) OCIs worked very well for me over many years and many millions of kms/miles. My trucks were always loaded to 42000kgs and I never had a differential or wheel bearing failure when using synthetic lubricants. Operating temperatures were usually less than 80C
condemnation limits will vary somewhat from Manufacturer to Manufacturer. It would be fair to say though that the "limits" are quite universal in that the concentration is the deciding factor
These are limits from Eaton concerning truck diffs:
Viscosity at 100C - 20% +/- from new
TAN - increase of 2 over new lube
Phosphorus - 30% decrease from new
Iron - 1500ppm
Copper - 250ppm
Chromium - 10ppm
Silicon - 130ppm and other WMs are high
Sodium - 50ppm
Aluminium - 150ppm
Water 1% by volume
I used this lubricant (Mobil 75W-90) and Castrol's equivalent for many years in my Class 8 trucks. I did not carry out OCs at all before 1m kms (620k miles). Both the castrol and Mobil lubricants performed the same - both are great products!
This UOA was from one diff (front of tandem) and taken at 1.04m kms (646k miles) over four (4) years:
Iron - 569ppm
Aluminium - 8ppm
Chromium - 2ppm
Copper - 40ppm
Lead - 5ppm
Silicon - 138ppm
Sodium - 10ppm
Tin - 2ppm
TAN - 2.4
Water - 0.15%v
Viscosity - normal
Most diff lubricants are changed out far too soon - water may be an issue with some vehicles however if breathers are submerged from time to time! "Unpracticed" lubricant contamination can occer too for the unwary!!!
The 1m (620k miles) OCIs worked very well for me over many years and many millions of kms/miles. My trucks were always loaded to 42000kgs and I never had a differential or wheel bearing failure when using synthetic lubricants. Operating temperatures were usually less than 80C