Each application darkens them a bit. Keep in mind brake dust and lighting.
They are gray, less dark in the light.
Also they stopped leaking air with treatment.
Gibbs also works however so does gun
oil. (All made to last and protect metal surfaces.)
Either way you will be good.
PS I never polish the lip. Like patina look and it really has the cast I like.
Best to you
BTW after reading a bit Gibbs is a gun
oil.