This is the third rear differential fluid change the car has seen. Mileage worked out to a tad longer (14.4k vs 11k) but overall track time was similar (22 hours vs 24 hours). The car has a dedicated differential cooler.
Blackstone highlighted that iron came down even further despite the longer run and everything else is steady. They attributed the aluminum to something "benign" like oxides. Confusing to see it continue to rise, but I don't consider it a wear metal for a differential. Open to ideas.
I'm now using Red Line 75w90 GL-5 gear oil instead of the OEM GM fluid.
Code
OIL ACDelco ACDelco ACDelco
MILES IN USE 14,465 11,057 2,958
MILES 28,480 14,015 2,958
SAMPLE TAKEN 3/24/20 10/20/18 7/3/17
ALUMINUM 174 111 40
CHROMIUM 1 1 1
IRON 123 138 107
COPPER 5 4 3
LEAD 1 1 1
TIN 0 0 0
MOLYBDENUM 1 1 1
NICKEL 4 3 2
MANGANESE 4 6 7
SILVER 0 0 0
TITANIUM 0 0 0
POTASSIUM 1 2 5
BORON 67 62 56
SILICON 6 7 7
SODIUM 7 7 9
CALCIUM 14 16 11
MAGNESIUM 8 4 4
PHOSPHORUS 2291 2103 2299
ZINC 18 16 20
BARIUM 0 1 3
INSOLUBLES 0.3 0.3 0.2
WATER 0 0 0
FLASHPOINT �F 390 380 380
SUS VIS 210�F 69.4 71.1 73.7
cSt @ 212�F 12.80 13.23 13.93
TBN 3.1
TAN 6.4 9.2
Blackstone highlighted that iron came down even further despite the longer run and everything else is steady. They attributed the aluminum to something "benign" like oxides. Confusing to see it continue to rise, but I don't consider it a wear metal for a differential. Open to ideas.
I'm now using Red Line 75w90 GL-5 gear oil instead of the OEM GM fluid.
Code
OIL ACDelco ACDelco ACDelco
MILES IN USE 14,465 11,057 2,958
MILES 28,480 14,015 2,958
SAMPLE TAKEN 3/24/20 10/20/18 7/3/17
ALUMINUM 174 111 40
CHROMIUM 1 1 1
IRON 123 138 107
COPPER 5 4 3
LEAD 1 1 1
TIN 0 0 0
MOLYBDENUM 1 1 1
NICKEL 4 3 2
MANGANESE 4 6 7
SILVER 0 0 0
TITANIUM 0 0 0
POTASSIUM 1 2 5
BORON 67 62 56
SILICON 6 7 7
SODIUM 7 7 9
CALCIUM 14 16 11
MAGNESIUM 8 4 4
PHOSPHORUS 2291 2103 2299
ZINC 18 16 20
BARIUM 0 1 3
INSOLUBLES 0.3 0.3 0.2
WATER 0 0 0
FLASHPOINT �F 390 380 380
SUS VIS 210�F 69.4 71.1 73.7
cSt @ 212�F 12.80 13.23 13.93
TBN 3.1
TAN 6.4 9.2