It would depend on the recipe. Some of our old recipes say salad dressing, and you can use mayo or miracle whip/store brand salad dressing. So anything that is mayo-based would use Miracle Whip (or mayo, since that's what I buy).
If I'm thinking of something for my salad, it's going to be ranch, bleu cheese, vinaigrette, etc
I had the same question about "oleo" when I first started using old recipes!