Actually the opposite, annealing softens the aluminum, increase its ductility:I’m not a metallurgist but how would annealing aluminium improve the seal? I was under the impression that softer metals are better for this purpose and wouldn’t annealing harden the metal?
Annealing (materials science) - Wikipedia
en.wikipedia.org
Never used one.How do you feel about plastic drain bolt washers?
Lack of stats isn't how evidence works.There is no reason you cannot reuse a drain plug gasket that is in good shape. Again, this has been done hundreds of millions of times without issue. That's a lotta evidence. I have no stats, but my guess is more have been reused at least once than not.
It's best practice for any mechanic who's worth a **** to replace copper / aluminum crush washers. These mechanics love lub-jockies that re-use these gaskets since it generates more work for them.
Aluminum / copper form a seal by being crushed. Sure when properly torqued there should be enough crush left for a second use, maybe.... maybe not. For less than $1 a year why is this even a debate?
What's next, reusing condoms?