Oil conditioner?

[VileKnight]

So the wife dropped her Rogue off at the local dealership on Wednesday for an oil change. We got her the maintenance package (i know...) so I assumed with the car having less than 5k miles I wouldn't have to worry about them trying to sell her additional crap for service.... boy was I wrong!

So I pick her up, and on the way home she tells me that "it's only going to be $30". I damn near stood on the brakes at that point. WTF is the $30 for when the oil change should be free you ask? Well, according to her it was to do with the air filter cabin - to clean the sludge off.... so thinking that someone just took advantage of my wife, I call the dealer right away. They explain that it's a conditioner for the oil to help reduce sludge buildup.

I'm not going to say I am a mechanic, but I can do some minor stuff like changing oil, plug, break pads, etc. Never heard of, or even seen a product like this on the shelves. When I Google this I see a lot of comments about how this stuff isn't really needed.

So is this actually a legit thing? Even if it was, how in the F would the car have a sludge problem in less than 5k miles? Would love some opinions from the community.