Best lubricant for car keys/locks?

[1997reduxe]

Hi all.
Recently I moved to Texas from PA.
I have been used to using graphite or graphite
oil in my car locks, and have to my knowledge
never experienced any problems.
Today I went to a locksmith store to get some
replacement keys and the graphite/oil,
but the salesman said that graphite was bad to use
in this area--that it is a pulverized solid and that in this
area/weather it would eventually clump and possibly
I assume block or hurt the lock at least somewhat.
(I have a 97 Subaru with old-fashioned keys.)
He suggested instead WD-40.
Is this the best idea for locks?
Any other ideas or suggestions?
Thanks so much.
'reduxe

[curtis73]

I have a locksmith friend who swears by a combination of a squirt of graphite powder and a squirt of WD40. He's been a locksmith for 32 years, so he might be on to something

['97ventureowner]

I live in NY and have been using graphite powder for over 20 years and my father had used it WAY longer than that before me without any issues. I've also used WD 40 when I didn't have any graphite laying around, so either or both should work fine.