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I have a 99 Se with 232k on it. I've recently noticed that once car is at operating temperatures the oil pressure gauge goes from 40psi to a little lower and the longer I drive the car it seems lower at high way speeds it's at 30-35psi and then coming to a stop it sits right above the red.

Could this be oil sending unit? Or just a tired 3800? Engine doesn't tick or smoke still runs smoove voltage gauge also dips when braking then bounces back and bounces with the blinker not sure if issue is related though.

The best way to check is to throw a mechanical gauge on it and compare the readings. It's possible the sender may be on the fritz, but I would be more inclined to believe it given the behavior.

Also keep in mind that many things can affect engine oil pressures, a big factor being oil age and contamination. How long since the last oil change? How long has this been going on like this?

Changed the oil at 231k and its at 232220k now I wanna say I noticed this about a month ago dont recall it ever being like this before I would've noticed.

The oil gauge clusters are notoriously inaccurate, hence the need for mechanical confirmation.

I forget the spec, but the rule of thumb is either 5 or 10 PSI per 1,000 engine RPM.

I had a Series 1 3800 with 242,000 where the oil pressure gauge had exactly the same behavior as yours, and the car ran like a champ, only junked it due to rust. Dont worry about it.

Well that's good to know! Im gonna put the oil pressure gauge on it also just to check for sure, but it runs great still like you're saying your car did!

Boreas wrote:10 PSI per 1,000 engine RPM.

^^^^ That's what you want.

You can check it mechanically if you'd like, but like Boreas said, it's likely nothing to worry about.