Paint & Body Work - prime and paint zinc plated motor mounts?

Live in Southern California. Should Zinc plated polyurethane motor mounts be etched primed & painted, or is the plating enough in the engine compartment to last w/out rusting? No experience w/ zinc plated polyurethane mounts. Maybe the plating has an equal life span as the polyurethane? Will the primer eat away at the polyurethane?

Mount similar to this. http://i201.photobucket.com/albums/aa249/blowdry2/motormounts.jpg

Thx.

Any input?:chuck-bal

Etch prime n paint them, won't hurt the poly, just won't stick to it so tape it off the best you can

^Thx. Next thing to do.