4.2 install low oil pressure

[Thestigmach1]

My 3.8 died so I decided to put a 4.2 in from an f150. Supposedly 150k miles on it and ran good when pulled. I did not hear it run unfortunately as it was already pulled. Install was very easy actually, i may do a thread on that, but I have low oil pressure. When cold at idle it shows around 40 then slowly works its way down to around 5 as it gets hot. I don't hear any valve noise or rod knock but it makes a slight squeaking noise when it gets to this point. I fear that the rod bearings are bad. Can anyone offer different opinions on that before i take the motor back out?

 

[6 Shooter]

5 psi at idle is a little low. More importantly is if the oil pressure rises when stepping on the gas pedal. That said, you could change the oil and put in 10w40 during the summer months which is thicker and will raise the pressure during idle.

 

[Thestigmach1]

5 psi at idle is a little low. More importantly is if the oil pressure rises when stepping on the gas pedal. That said, you could change the oil and put in 10w40 during the summer months which is thicker and will raise the pressure during idle.

It does rise but only to about 20. Which still seems super low to me. But I can't seem to find anywhere ehat the correct pressure for these is. Also note that fresh oil change with 30 min of run time and the oil is black as night. I found that strange.