Whatever funky oil is used (just use mineral oil please). I've tried all kinds of crap, even wood-spoon wax.
If dirty, clean 1st. Then oil.
Be careful to not leave it on too long (to let it soak into the inlay). Just smear and wipe (2+ times wiped if needed)(& NO soaking!).
If oil is on too ling you will get the oil embedded into the inlay and will see it forever.
Been there (especially with BCC chips), but fortunately no inlays dropped off).
Still: over oiling is chip abuse.
Edit: i never tried motor oil...
If dirty, clean 1st. Then oil.
Be careful to not leave it on too long (to let it soak into the inlay). Just smear and wipe (2+ times wiped if needed)(& NO soaking!).
If oil is on too ling you will get the oil embedded into the inlay and will see it forever.
Been there (especially with BCC chips), but fortunately no inlays dropped off).
Still: over oiling is chip abuse.
Edit: i never tried motor oil...