Mobil 1 15W50 SN VOA

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Originally Posted By: chubbs1
WAY THICKER than the SM version. Wait a second, is the SM 5w50 and just mislabeled? I am confused.


Me, too. I'm not even talking about the tested viscosity. Blackstone gives the expected viscosity range for SN 15w-50 as 17.7 to 20.6 cSt. They give the expected viscosity range for SM 15w-50 as 14.5 to 17.0 cSt. Perhaps I'm new to reading oil analyses, but I would think that the expected weight range of a 50 weight oil at 100 C would be the same, regardless of brand or API specification.
 
Originally Posted By: buster
Only 924ppm of Ca.


Ca and Mg are definitely being supplemented with something not seen in these VOA's.
 
It contains about 200 PPM less zinc than the SM Mobil1 15w50. That disturbs me, because much high ZDDP is one of the things Mobil bragged about with their 15w50 oils.

At least it is better than the Xw30 and Xw20 oils.
 
Wow, a huge difference from the SM report for Zinc/Phos levels. What in the world?...
 
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What is the deal with this Cal/Mg tradeoff?? Any chemists in the house?

I tried asking mobil but got the standard nsa-like response.
 
Magnesium detergents can give a higher TBN than equal mass of calcium detergents. This allows them to lower the sulfated ash test value while minimizing the loss of TBN. But keep in mind that detergency over the life of the oil depends on more than just initial TBN. Calcium and magnesium and sodium-based detergents behave differently.
 
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