so after i installed the oil pressure and temp gauges, i've been monitoring them every once in a while as i drive, as i idle, when the engine is hot, cold, etc.

on cold starts, especially on colder mornings, pressure at idle hits up to about 65 psi, then as the revs start to drop, it flattens out to about 20 psi...starting the engine when its warm peaks at 50 psi and then flattens back out to 20

the past few mornings, especially monday and yesterday when it was very cold, i noticed that after the revs flattened out at idle (at about 700RPM) the oil pressure is low...like, very low...like, not much above 5-10 psi if that...it freaked me out a few times so i pulled over and shut the truck off and cranked it back over, the pressure went up to about 20 psi for a few seconds, then back down...

i'm now trying to figure out if there is a problem with the gauges or wiring (will a bad ground from the gauge cause this?)...is this normal behavior for the oiling system? or is my engine hurting? it does see higher pressure while cruising at highway speeds, yesterday i cruised about 5 miles down the highway after work and it sat at ~40psi the whole time...sometimes just before i shift it hits ~60 psi....

the low oil pressure dummy light hasn't come on at all....

the temperature seems to be fine, it rises slowly and peaks at about 170* after 6 or 7 minutes, never seen the needle past that

halp

according to alldata, 9psi @ idle and 60-65 at 2000 RPM is healthy....i guess the engine is healthy, just seems too low

This seems normal to me, book calls for 11psi for mine. But I also had an 89 pathy 3.0, I wouldn't think there would be too much difference to the xterra. Mine would get as high as 70 to 75 on really cold days and about 7 on really hot ones at idle. Hope that helps you a little.

Sounds normal to me too.