Wow, I picked up on/learned about a couple things about synthetic oil brand tiers today. I was under the impression the black bottle Castrol was/is superior to the Gold bottle. According to the marketing doesn't seem so. As for topic, been couple threads (one involving Amazon) that have alluded to if not stated the supersession of Magnatec with GTX Full Syn. I thought the latter advertising was "4x better" (at something) not 6x ( at something) like Magnatec. But, I might be mistaken somewhere in that assertion.
Also like previous poster noted, the new-ish Pennzoil Full Syn, this AM I mistook it for PP with a quick look seeing it for sale a WM with a decent and lower jug price. Then after looking closer saw black label PFS is not same as PP. Who knew, not me. Best I could tell, PFS unlike PP and PUP is NOT made from natural gas.
Hard to keep up.