quote:
When I blasted Synthetics, I did not mean Castrol Syntec GC 0w-30, which in any case is hardly a universally-available, off-the-shelf item you can get at any Gas station like Valvoline or Castrol GTX. It is more of a Cult product.
Most of my negativity was directed at the stuff that comes in flimsy silver bottles, with the fragile, leaky cap.
I've had 4's and 5's in my mineral used oil analysis for Fe (ppm). Most of the Synthetic used oil analysis that I've seen show far greater Fe content than 4's and 5's, often double, and sometimes triple or more.