Castrol GTX 10W-30 Premium Conventional Motor Oil, 5 Quarts

I switched from the oil in the yellow bottle that starts with the letter P and I tell you I think my truck is running better with this oil in it. It seem to reduce engine noise, feels more smooth. I know I had about 3-4k miles on the last oil change so dont know, either im seeing and hearing things or something changed.

Back in the 80s we had a commercial where a group of nerdy scientists in lab coats set up a bunch of 4 cylinder engines in a white laboratory, filled them with different brands of oil. They then ran the engines and then drained them of oil. They continued to run the engines until, one after another, they blew up. The engine that had Castrol in it continued to run long after the other's siezed up with the lab coat guys looking on astonished. Of course that's just a commercial but I was a little kid and that advertisement had more effect on me than some NASCAR driver with huge sideburns trying to sell me Pennzoil or another NASCAR driver with a mullet selling me Valvoline. In modern times nobody except Lucas talks about how it can save an engine, and all oil brands are pretty much generic and the same. Royal Purple goes out of its way to say how purple food coloring somehow makes their product superior, but it's just purple food coloring, there's nothing chemically different about thier oil. They even went so far as to claim in a few commercials that they use nanotechnology to formulate their oil. Wow! A form of technology that is currently science fiction because we haven't even gotten to that point? But they're already allegedly using microscopic robots in their oil!!! Amazing! That must be what the purple food coloring is! Little robots from Star Trek the Next Generation! They removed the zinc from all the oil a few years ago but, surprise surprise, you can buy an additive to put the zinc back in!!! I guess the real question is why did they take it out and why can you now buy an additive to put it back in? I still buy Castrol, more out of stupid brand loyalty than anything else, and the fact that it's usually on sale, but it certainly doesn't instill the confidence that it will out perform all other engine oils. And to be honest, probably never did, but it was great advertising!