Hi, I have a 1998 with a 3800 and a stick. A couple weeks ago (in the Michigan winter) I started the car to find the oil pressure was about 45, when its normally about 60 from a cold start in winter. Ever since then its been a bit lower than usual, around 40 on the highway and as low as 30-35 at warm idle. This is about 15 less in any situation than it had been before. What could have changed so suddenly? Any input is appreciated.

 

It should move around depending on the RPM's. Rev up the motor and see where the oil pressure goes to.

 

Assuming you have not changed the oil to a different weight than what you normally run, I would guess the oil sending unit may be getting weak. Put a mechanical guage on it to verify oil pressure.

 

Thanks. I realize its supposed to change based on RPMs and engine temp. My concern is just that it is now (and suddenly became) about 15 PSI lower in any condition that it had previously been in the same condition. It's not in the danger zone yet, but I'm going to slap a mechanical gauge on there when I get the time, and we'll see if that works. Thanks for the replies.

 

Check the oil itself and make sure there are no grey sparkles in it. Metallic looking oil is not a good thing.

Massey

 

Most of the time sudden changes in oil pressure are gage system issues. The factory setup is not very reliable. These gages are only a little better then the dumby light. You can put a mechanical gage on it but your 15 PSI differents could be only 5 real PSI change or it could be a 30 PSI change.

Drops in oil pressure due to something like over heating or right after reving the motor high can indicate something has more clearance then before. Its preety rare for a motor to really drop oil pressure with out some change or event.