4 ft.hairline crack in stucco....any advice?

All stucco cracks. In the newer houses they are putting in control strips to minimize the cracking, but it still happens. If it isn't moving, your fine.

Absolutely true.

However, if the stucco is painted or sealed, you can buy an elastomeric masonry paint that is made to cover just that. Have it tinted to match and you are on your way.

Robert

Or caulk using latex caulk and then paint over that. A painter frend of mine told me to put some Alex Plus caulk on a wet rag and rub the area to fill hairline cracks then you can paint over that. Latex caulk can actually be thinned that way

Stucco patch will not work unless the crack is big enough to hold enough material.

That's what I do. Works well.

Our stucco on concrete block was painted over 5 years ago, and the contractor used brushable caulk on the many fine hairline cracks. None of them have reappeared, and the caulk doesn't show through the paint. There is also a latex stucco patch that works very nicely on larger defects, comes textured and plain.