16 October 2014

Oil Analysis - BMW Performance 20W50 vs. Porsche Classic Motor Oil 20w50 (PART 2) - Conclusion

Well, results are in. I'm very surprised.

Besides just getting a test on the Porsche oil, I wanted to compare the new BMW formulation (blended by Castrol/BP), with the old BMW blend by Spectro and the Castrol 4T conventional oil (to see if all the BMW oil is now is just re-badged Castrol 4T - a theory I was pretty certain was going to prove true). Here are the old results Kurt got for BMW and Castrol a few years ago for the BMWMOA (approximates based of his charts).

BMW Conventional 20w50 (Spectro Blend)
Zinc: 1375ppm
Phosphorus: 1100ppm
Viscosity at 100C: 18
TBN: 7.5

Castrol 4T Conventional 20w50
Zinc: 950 ppm
Phosphorus: 750ppm
Viscosity at 100C: 20
TBN: 8

Here's the new results. NOTE: Although TBN was requested for the testing, I can only find the TAN on my test results, so for now that will be omitted...

New BMW Conventional 20w50 (Castrol Blend)
Zinc: 1207ppm
Phosphorus: 1014ppm
Viscosity at 100C: 18 .7
TBN: n/a

Porsche Classic Motoroil 20w50
Zinc: 883ppm
Phosphorus: 927ppm
Viscosity at 100C: 19.1
TBN: n/a

Based on these results, it appears that BMW does indeed have a different formula than Castrol 4T, which I was pretty surprised about. It also appears that the Porsche is lacking in the ZDDP area - so maybe the Germans really do believe Americans are the only ones concerned with ZDDP. The one thing Porsche had going for it was the Calcium level - 2026ppm compared with 636ppm in the BMW oil. BMW oil was also full of Magnesium and Porsche had almost none. That being said, I will not be using the Porsche in my airhead.

Attached are the full analysis results for the new BMW oil:


And the Porsche oil:


  1. Thanks much! Very informative.

  2. No problem, glad I could help

  3. Awesome info! Porsche wouldn't give any information at all.