What is the best recommendation for painting weathered aluminum siding?

Aluminum siding tends to chalk after weathering. The chalk should be removed prior to painting by cleaning with soap, water and a soft scrub brush. High pressure power washing can also be effective if done properly. Thoroughly rinse the surface and allow to dry before painting. If no chalk remains, an exterior acrylic latex house paint may be applied directly. If light chalk remains, prime with a chalk penetrating acrylic latex primer. If heavy chalk remains, prime with an exterior alkyd house paint primer. Finish as desired. A satin finish most closely approximates the original factory finish sheen. Two coats of finish will provide a longer service life.