If you anneal the washers with a Bernz-O-Matic then sand them on a flat piece of glass and fine sandpaper you should be able to reuse them just fine, but that's a lot of trouble so just get some new ones and be done with it. Damned if I could find any when I replaced the fuel filters on my car though.

__________________
'02 BMW 325i
'85 300D 450k
'93 190E 2.6 170k(killed by tree)
'08 Ducati Hypermotard 1100S 6k
'06 Ducati S2R800 14k(sold)