I came across this "linseed oil finish". It's boiled linseed oil applied as an option to the exterior vs powder coating, on offset smokers.. The manufacturer claims ~ 80% of their pits are specked with this finish..
I had a look @ the procedure. Starts out with well prepped metal to which the boiled linseed oil is applied to the heated pit then cured. Similar to seasoning cast iron cookware..
Endurance wise: the claim is said to be excellent. Last for years. Visually: the claim is that of patina..
I would think that touch ups would be rather easy- if required.
It might be considered as an optional finish for a non stainless pit refurb.
A concern may be burn-off in a high heat area, otherwise it should be a good protectant/finish.