unklrod, the only way to keep the rust from coming through the springs is to take them apart and clean them. This is just my opinion! I took mine apart and cleaned them then primed and painted them. I might add I also used the polyliner in between them to help them flex easier as they had a fair amount of wear on them.
I am also a big fan of the POR15. Tough stuff and a quart will put two coats on most size chassis. Pour out small amounts at a time to keep it from starting to set up on you and keep it covered well. Someone here suggested drilling a hole in the top of the can and after pouring some out to put some tape over the hole. Less mess and helps keep if from drying out.
The stuff will coat your lungs to so be sure you have good ventilation, old clothes and gloves!
