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2006 Cadillac CTS-V Used Oil Analysis Report

Differential Fluid


C66 Racing team owner Brad Neff bought a 2006 Cadillac CTS-V as his daily driver in the fall of 2006.  The car was a used corporate car that had 7780 miles of use.  In an attempt to obtain information on the differential's performance over time, as well as how the factory fluids compared to aftermarket alternatives such as AMSOIL, the team intends to draw used oil samples after each fluid change and submit them to  Blackstone Laboratories for analysis.


Used Oil Analysis History:
Oil Factory Fill       Universal Lab Averages
Miles on oil 10,636        
Miles on unit 10,636        
Sample Date 6/10/07        
  ppm       ppm
Aluminum 15       10
Chromium 14       3
Iron 1107       517
Copper 177       16
Lead 21       3
Tin 14       1
Molybdenum 3       2
Nickel 22       10
Manganese 101       30
Silver 0       0
Titanium 0       0
Potassium 10       5
Boron 200       92
Silicon 33       40
Sodium 11       43
Calcium 3       34
Magnesium 2       4
Phosphorus 3898       1490
Zinc 127       374
Barium 37       4
SUS Viscosity @ 210F 68.4       Range ~67-80
  Actual Blackstone Report        


Initial Fill

The differential fluid initial fill was GM Factory Fill synthetic 75w90 gear lube.


Oil Change 6-10-07

After 10,636 miles of driving, the differential fluid was drained and replaced with AMSOIL Severe Gear Synthetic Extreme Pressure Lubricant 75w90.


Blackstone's comments on the sample result:

We normally expect to see high wear in factory fill differential sample, though these levels are a little excessive, even for that.  Iron was the dominant metal and shows some serious wear at steel parts.  Chrome, iron, and nickel are all alloys in steel, and should read well below average considering the short oil run.  Universal averages show normal wear levels after about 29,000 miles oil use.  Copper, lead, and tin show poor wearing bronze parts like a bushing.  Suggest having this oil changed out if you haven't do so already and resample in 5,000 miles.


Our evaluation of the used oil analysis report:

- As evidenced by the SUS viscosity at 210F, the gear lube remained in grade for a 90 weight gear oil and did not shear low out of grade or thicken out of grade.

- As evidenced by the ppm values for the wear metals, primarily iron, chrome, nickel, copper, lead and tin, the differential exhibited wear 114 - 1300% above the universal lab averages.  This is particularly concerning given that the gear lube only had 10,636 miles on it, compared with the universal average of about 29,000 miles.  Given the problems GM has had with the CTS-V differential, these high wear metal readings may be indicative of problems to come for our differential.


Understanding the used oil analysis report


These two links to pages on Blackstone Laboratories website provide background on the elements in the used oil analysis report, as well as how to review and understand the report:

Understanding the Elements

Understanding Your Gas/Diesel Engine Oil Report


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