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1999 Corvette C5 Used Oil Analysis Comparison

German Castrol vs AMSOIL Series 2000


C66 Racing conducted a used oil analysis comparison of German Castrol 0w30 vs. AMSOIL Series 2000 Synthetic 0w30 from March to October 2005 in a 1999 Corvette C5 Fixed Roof Coupe (FRC), the predecessor to the Corvette C5 Z06.  Our interpretation of the results is that both of these are excellent oils, and the AMSOIL Series 2000 Synthetic 0w30 is a viable option for those that desire an American made alternative to German Castrol 0w30.


C66 Racing has been racing a 2002 Corvette Z06 in the SCCA Touring One Class since 2003.  As such, we spend a lot of our free time on the various Corvette Forums on the internet.  After reading many of the oil related threads on these forums, it rapidly became apparent that German Castrol 0w30 was a favored oil of the forum members.  It is widely believed on the oil related forums that the German Castrol 0w30 uses a higher quality basestock than the Castrol Syntec made for the U.S. market, though Castrol has neither confirmed nor denied this in response to forum member queries. 


With the assistance of a volunteer from the Corvette Forum who had been a long time user of German Castrol 0w30, we had four used oil samples sampled and analyzed by Blackstone Laboratories, one with German Castrol 0w30, followed by two with AMSOIL Series 2000 Synthetic 0w30, and finally another with German Castrol 0w30.  The car was a 1999 Corvette C5 FRC (shown above) with a 5.7L LS1 motor, modified with a Blackwing air filter, an LS6 intake, and a Borla exhaust system.  The car had 46,754 miles on it at the start of the test, which put it past the point where motor break-in would skew the results.  The owner had been running a K&N HP 1007 oil filter, and to minimize the variables in this comparison, the same type of oil filter was used for all four samples.

Oil German Castrol 0w30 AMSOIL Series 2000 Synthetic 0w30 AMSOIL Series 2000 Syntethic 0w30 German Castrol 0w30 Universal Lab Averages (LS1 motor family)
Miles on Oil 5,069 3,513 3,281 3,126 (4,200 Average)
Miles on unit 61,744 56,675 53,161 49,880  
Sample Date 10/28/05 6/24/05 5/06/05 3/11/05  
  ppm ppm ppm ppm ppm
Aluminum 2 1 2 1 4
Chromium 1 1 1 0 1
Iron 8 5 6 6 14
Copper 12 11 13 9 38
Lead 4 2 3 2 7
Tin 0 1 1 0 2
Molybdenum 2 2 4 0 54
Nickel 0 0 0 1 1
Manganese 1 0 0 0 1
Silver 0 0 0 0 0
Titanium 0 0 0 0 0
Potassium 0 0 0 0 1
Boron 6 31 38 2 80
Silicon 12 10 10 4 9
Sodium 1 1 1 2 7
Calcium 2863 2036 2410 2692 2274
Magnesium 214 721 795 121 367
Phosphorus 790 904 1012 721 749
Zinc 971 1073 1144 858 893
Barium 0 0 0 0 0
TBN 3.5 7.7 7.3 4.2 Min 1.0
SUS Viscosity @ 210F 66.7 62.4 64.5 65.2 Range ~56-68
  Actual Blackstone Report Actual Blackstone Report Actual Blackstone Report Actual Blackstone Report  


Our evaluation of the used oil analysis reports:

- Though the AMSOIL Series 2000 TBN was notably higher than that of the German Castrol, both oils had active additive left as evidenced by their TBN, and could be safely used for considerably longer than the typical 3,000 mile oil change intervals in use by most motorists. 

- As evidenced by their SUS viscosity at 210F, both oils remained in grade for 30 weight oils, contrary to some statements we've read on the web indicating that a 0w30 will shear low out of grade, and others claiming that AMSOIL has a tendency to thicken out of grade, neither of which actually occurred in this test.

- As evidenced by the low ppm values for the wear metals, primarily aluminum, iron, copper and lead, which were all 25-50% of the lab's universal averages for this motor family - both oils performed very well.  No notable increase or decrease occurred in the ppm values of the wear metals when switching from German Castrol 0w30 to AMSOIL Series 2000 Synthetic 0w30.  Though a slight increase in wear metals was noted on the final Castrol sample, this can attributed to the slightly longer oil change interval used on this sample.  Thus, our conclusion is that the AMSOIL is a viable option for those who prefer an American alternative to the German Castrol.


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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