L10 Cummins ISSUE- one day great oil pressure and next day the alarm goes off. Every day is a gamble

Like title says, one day I start truck and oil pressure is beautiful and the next day it’s horrible it goes below and sets off alarm but will increase with rpm but not good still

Everyday it’s a gamble if it’s going to be good or not.

I’m lost on what it can be so I’m consulting with some experts on this motor??

Thanks so much I’m advance for any help or insight

 

My mechanic did for me and on days it’s good it tests great but on the bad days it comes out low and it tends to smoke a bit more when it does that.

 

Thank you, we have checked them and it’s good. Everything looks good but everyday it’s a gamble if it’ll run right or not. However it starts the day is how it’ll be all day no matter what we do. It’s weird and why I’m stumped

 

Thank you for your help. Yes day one when it happened i went ahead and changed oil and did a flush just in case to it.
It’s right at startup when it works or does not. And once it warms up it doesn’t change regardless of temp. I mean on a good day pressure goes down when warm but nothing out of ordinary

 

I didn’t do the test myself but mechanic said he tested on manual gauge and it was accurate to what was stated above