I remember Slick50, Prolong, ZMAX, and STP (many years ago). No thanks. My regular oil changes are doing just fine. Sorry, I don't buy the sticky climbing oil theory. Their little display. What's in the comparison side? Gold colored piss water? Who knows? The only oil I ever noticed poor performance from was Pennzoil. I used it when I first started driving. Probably advertising! Hmm... The oil pressure would drop A LOT when warmed up. I switched to Quaker State. It was much better. Then I found out they were bought by Pennzoil. No thanks. Switched to Valvoline. Have no complaints. A Shell Oil engineer talked to us when I was in A&P school. He said to look on the back of the oil container. See what API standards it has met. Go with that.
https://www.api.org/products-and-ser...s#tab-gasoline