Great report! The 100c viscosity held in very well, I wonder what the TBN was. I recently did 6400 miles on the synthetic blend 5w30 magnatec, on an 07 cobalt ecotec. TBN was 6 and 100c cst was 10.5.
Could have done thousands more miles.
Magnatec is only $17.88 at Walmart, great deal for this oil.
I wonder if the synthetic magnatec polymers are contributing to this oil holding it's viscosity so well, and reducing iron wear.