Yeah, I've seen tons of opened engines in my lifetime and you can easily see the difference between those who had cheap gas run through them all their lives vs ones that were fed with good additives, especially techron. Engines that were run with strictly chevron gas had minimal carbon deposits on their pistons and valves, while cheap gas ones would be fouled to shyt with crusty gunk all over them. I only run Chevron 91 in my 2001 740 and I feel like it's a big reason that it's still running like a bat out of hell with 220k on the original engine. If you plan on keeping a car for a long time, don't run shytty gas through it.