Proper grip finish
 

I am aware that this is a Luger forum, and have one currently being "rehabilitated" Thor. I just got a P38 from 1944, with original grips, but want to shoot the pistol, so I took the bakelites off and want to use repro walnut grips. My request is this: what would the Mauser factory have finished the grips with? Lacquer, Boiled Linseed oil, or something else, considering the probably made wooden grips for some other firearms as well. Any and all advice/help is welcome. Thank you!!!

I'm not clear on your question.
Are you asking about the correct original finish on Nazi walnut P-38 grips? That's all news to me., but anyway, we have a grip wizzard here, Hugh Clark, that all grip related issues go to. Search him up.
dju

using substitute grips
 

It appears to me that if you wanted to protect your original grips the easiest thing to do is to purchase another set of P-38 grips and use them.
Jack
:typing:

LEAVE IT ORIGINAL! You might loose or breaks the original pair and not to mention the original grip screws. They were put there for a reason!

if going to shoot it, then changing to some wood grips is not bad

Linseed oil works well on luger grips, gives a light sheen but not bad.

You could also buy some P1 plastic grips, but if I was putting on replacement grips, I would prefer wood also :)

The factory finished the P08 grips with boiled linseed.

I would get a set of repro plastic P38 grips for shooting. Looks much better imho.