Originally Posted By: walk23
What triggers the need to start such a cycle without having peeked into valve covers?
The BITOG herd instinct.
One or two members post miraculous results (real or imagined) from the flavor of the month cleaner, and a lot of other members jump on the band wagon, break open their wallets, and then waste their money for something that does nothing more than give them a placebo "feel good" effect.
The same thing happens with other additives, and even oils. What's popular today will fall out of favor and be replaced by another miracle-in-a-bottle product in a year or two.
I remember when AutoRX was the darling product on here-people were paying a ridiculous amount of money for something that has now fallen out of favor and most realize that it simply doesn't do much of anything.
The same miracle cleaners today will be kicked to the curb in a year or two when people realize that they too are a waste of money.