2nd rear diff UOA on the wife's new to us Tahoe. Oil was changed at time of sample. Blackstone comments at the bottom.
Make/Model: GM Differential
Vehicle: 2004 Chevrolet Tahoe
Code:
OIL Amsoil 75w90 Unknown
MILES IN USE 25,128 Unknown
MILES ON UNIT 148K 123K
SAMPLE TAKEN 3/18/13 5/3/11
MAKE UP OIL 0 0
ALUMINUM 3 4
CHROMIUM 1 2
IRON 255 672
COPPER 7 28
LEAD 0 1
TIN 0 0
MOLYBDENUM 0 3
NICKEL 4 11
MANGANESE 6 26
SILVER 0 0
TITANIUM 2 0
POTASSIUM 0 0
BORON 100 179
SILICON 162 13
SODIUM 6 34
CALCIUM 9 42
MAGNESIUM 3 3
PHOSPHORUS 913 1683
ZINC 21 68
BARIUM 0 1
SUS @ 210F 88.3 69.0
Visc @ 100C 17.57 12.70
Flashpoint 415 370
Fuel % 0.0 0.0
Antifreeze % 0.0 0.0
Water % 0.0 0.0
Insolubles % 0.5 0.2
TAN 1.8 NA
The new sample from your differential is looking better than the last one. Iron and copper made huge improvements and now compare favorably to universal averages. They show typical wear levels for a GM differential after about 32,400 miles on the oil. Silicon is kind of strange find. It can show abrasive dirt, but with wear this low we're betting it's an anti-foam additive used by Amsoil, or maybe a silicon sealer. No moisture was present and insolubles are okay at 0.5%. We have to do a TAN on diff fluid too and that read 1.8. Run the next oil 30-35K miles.
Make/Model: GM Differential
Vehicle: 2004 Chevrolet Tahoe
Code:
OIL Amsoil 75w90 Unknown
MILES IN USE 25,128 Unknown
MILES ON UNIT 148K 123K
SAMPLE TAKEN 3/18/13 5/3/11
MAKE UP OIL 0 0
ALUMINUM 3 4
CHROMIUM 1 2
IRON 255 672
COPPER 7 28
LEAD 0 1
TIN 0 0
MOLYBDENUM 0 3
NICKEL 4 11
MANGANESE 6 26
SILVER 0 0
TITANIUM 2 0
POTASSIUM 0 0
BORON 100 179
SILICON 162 13
SODIUM 6 34
CALCIUM 9 42
MAGNESIUM 3 3
PHOSPHORUS 913 1683
ZINC 21 68
BARIUM 0 1
SUS @ 210F 88.3 69.0
Visc @ 100C 17.57 12.70
Flashpoint 415 370
Fuel % 0.0 0.0
Antifreeze % 0.0 0.0
Water % 0.0 0.0
Insolubles % 0.5 0.2
TAN 1.8 NA
The new sample from your differential is looking better than the last one. Iron and copper made huge improvements and now compare favorably to universal averages. They show typical wear levels for a GM differential after about 32,400 miles on the oil. Silicon is kind of strange find. It can show abrasive dirt, but with wear this low we're betting it's an anti-foam additive used by Amsoil, or maybe a silicon sealer. No moisture was present and insolubles are okay at 0.5%. We have to do a TAN on diff fluid too and that read 1.8. Run the next oil 30-35K miles.