06 6.0 Low oil pressure

[Ultradog]

I tried to search but the search box keeps disappearing on me.
Pardon me if this has been asked a hundred times already.
06 2500 HD 4X4 with 6.0 and 185K miles.
I have low oil pressure on startups.
Get a warning notice on the info screen.
It is very bad in these below 0 temps.
If I let it warm up for about 10 minutes it comes up to about 35 and stays there.
What is the problem and what is the fix?
Thanks for any info.
Jerry