How long do vinegar based salads last?

Question

I've never kept home made ones longer than a week, but the grocery store puts an expiration date of 3 weeks or even longer on them. Do they use some kind of preservative? (Besides vinegar)

Specifically, I'm speaking about german potato salad.

Answer 1

That's right, they don't just put vinegar in ...

I doubt they'd tell you, what they use, but try :)