2017 Corvette / 14.4k / ACDelco 75w90 gear oil

Joined
Apr 19, 2010
Messages
13,663
Location
Frisco, TX
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
 
redline lubes are as good as it gets + besides protecting more they last longer. only downside of excesive changes is $$$
 
Any idea how much is left behind in the diff cooler when you change it? I'm looking to change my 2017 Grand Sport soon if anything because I'm bored.
 
Originally Posted by RhondaHonda
Any idea how much is left behind in the diff cooler when you change it? I'm looking to change my 2017 Grand Sport soon if anything because I'm bored.


Not sure, but when my shop changed it out, I gave them the gallon jug and they said they used "most of it". I can't remember if this is the process for the diff, MT, or both, but it involves putting fluid in and then putting the car in gear and running it at low speed for like 10 minutes -- then topping it off.
 
Thanks for posting this. I'll keep an eye on your UOAs to compare to mine since I also have a C7
smile.gif
 
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