@Ferrum1Whereas, when writing a do-over set firmly in a particular time, the opposite matters. In 1980, it matters a great deal that the computer received as a Christmas gift was an Apple II+ and not, say, a TRS-80. Or it could; the computer admittedly gets such short shrift that maybe it doesn't matter. Yet, to most readers aware of the time, it would be weird to not know what sort of computer it was.
And, as mentioned before, for a high schooler's used car, make and model matter. There's no reason to generalize it; it's a specific type of car.
On the other hand, those are unusual, high-ticket items. The type of shampoo matters not at all, so it's 'shampoo'. So far clothing brands don't matter; neither do store brands for the most part.
On the other hand, this discussion just reminded me to check and, lo and behold, I've got some references to 'Walgreens' that would be better off as 'drug store'. Time to edit! Radio Shack, however, can stay Radio Shack; some things must be as they were.