Ok so i have super low oil pressure, the lowest end of the little white scale. At start up is 40-45 and after driving for 5-10 minutes drops to the little white mark. I have changed the oil pressure switch, oil pump, and the pick up thinking that those were the problems, they were'nt. So what else could it be? Truck has 260,xxx miles on it but it really shouldn't madder after I replaced those parts... Running out of ideas, trying to see if one of you guys can help me.

 

As your motor gets more miles, it loses oil pressure. It could be blow by on the rings.

 

main bearings........................... get you check with a mech gauge?

 

Your right about motors losing oil pressure over time but blow by at the rings has absolutely nothing to do with oil pressure.

At that many miles you could have bad lifters, and/or just loose bearing tolerances. If the motor is running good and doesn't make any noises then just run it till it blows. You probably still have a good number of miles in it.

 

With that many miles it does have wear on the bearings for sure.
If it don't use much oil you could put main and rod bearings in it run it for quite a while.