When can sour cream NOT be replaced by plain yogurt in recipes?

[MSK]

Is there a rule of thumb?

I always seem to have the yogurt on hand. Not true of sour cream. And.... the nonfat version of plain yogurt seems healthier and a better texture than even lowfat sour cream. so it's always my preference.

But when would it not be recommended?

[todao]

Plain yogurt has only a trace of fat, whereas sour cream is typically about 18% fat. Where fat is an important element in the recipe it will make a difference. Otherwise, I use them interchangeably.

[Joebob]

Mountain High Original is 3.25%. Is that a trace?

[chowser]

I use them interchangeably in baking but only use the full fat versions. I can go lower fat with Fage yogurt because it's richer but still like the full fat version better.