2005 chevy Silverado, was driving back from sisters when oil pressure went up and speedometer went down. Got oil changed was fine for a month or so and now it's doing it again. It's over 80 psi even when off. Safe to drive? It's my only vehicle

 

Welcome from Florida. You can try a mechanical oil pressure gauge to see if the reading is accurate. More than likely you have bad stepper motors in the gauges. This was a common problem from around 03 to 06.

 

1) An electrical problem or bad guage could cause it. GM here is famous for "chinese guage issues". "cluster F(*# one piece". in that case if you confirm this by checking your oil pressure resistance: do nothing. don't fix it not worth it. but do check and clean all grounds everywhere on the vehicle: it DOES need it. and new brake and gas lines maybe.

2) High oil pressure could case it

normally it'd be if i remember 50-60psi when cold, then the ball breaks in the oil filter and it drops to 30-40 psi after warming.

You'd usually hear "your lifters making noise" if oil pressure is too high. If you filled your oil to "Max" while cold, that'd be too high and you'd hear a little lifter noise and be say over 60psi on cold and fall to 60 when warm (way too much!!).

when you fill oil COLD or (luke warm), on any car ever made, MAX MEANS MAX: hot. So fill it 1/2 way between low and high lines: when the car gets on highway it will be around max.

 

* make sure to clean wires that have oil all over them (ie, the oil pressure switch). but ask a mechanic how to clean an engine without cracking the motor or dousing electrical parts with too much water

* test your oil sensor (hopefully without removing, with a volt meter, see youtube for it). you may want to hook up "long leads" so you can monitor it. BUT THAT CAN GO WRONG. SO ... get yourself an ODBII unit and use the reading on that if it has oil pressure on it.

* if the oil pressure sensor is good your free to ignore the dash