The older white vinyl siding is looking greyish & no amount of labor with soap & water seems to help it become white again! Anyone know if white vinyl siding can be painted?
yes it can.
go in the store and ask
Here is a link that might be useful: vinyl siding
VinylSafe is a good option for painting siding. Even tho it's formulated to manage energy/heat accumulation, I'd err on the side of cautious and choose a light color to paint the siding.
If you know the manufacturer of the siding and can look up the color specifications and/or warranty, that would be ideal. Somewhere in the documentation for the siding it will give you spec's for LRV. For example it will say something like: Siding can be painted. Colors must have a LRV above 55. Failure to follow painting instructions will void all warranties.