I have consistently heard over the past two years that Mobil 1 was dumbed down about the time of the Exxon/Mobil merger. To the extent that it is presently a blend and not a pure
synthetic.
I still see M-B, Porsche and many others pasting Mobil 1 labels on their race cars. I wonder if that means they are using it in the motors? I would assume nothing.
I have always had good success with
Amsoil. And in years past, I never had a problem with Mobil 1. I change the
oil way too early usually, based on the analysis reports. But then I am four standard deviations to the old side of the bell curve around here. It works for me. The true synthetics tolerate heat far better than the cheap stuff though.