For years I used GTX back in the late 90s to early 00s and then at some point switched to M1... next I went with PP when it became the big thing here. I haven't really used Castrol in forever and been wanting to use it again. The car that the Magnatec is in has mostly been sitting because I need to swap the transmission as it's been making noise ever since I purchased it but has progressively gotten worse. With it being parked so much it should really put those molecules to work.