Hey all, I have a 305TBI with 27k miles on it. I run Mobil 1 Synthetic 5w30.

Anyway, when I start the car, the oil pressure stays arount 40, but as the car gets hotter and hotter it drops while idling. Now, no matter what the temperature of the motor, when ever I hit the gas, it does go right back up to perfect pressure, but at idle, it will go as low as almost into the start of the red. But say, at 2k RPM, the pressure will be at 30.

Also, I just replaced the oil pressure sending unit, and it did nothing.

Is that just normal for the Synthetic or motor?

Thanks!

Chris

 

I'd probably run 10w30 next oil change. The way you've got it is fine, though.

 

that's pretty much how it should act.
more rpm= more psi
cold oil = more psi
hot oil= less psi

 

My 305 TBI did the same thing. Had 113k miles tho. I think my bearings were going out. The pressure would drop enough to sometimes kill the car. Oh well I have a new 350...never goes below 30psi now. Except when the car is off

 

I had a similiar problem with my 88 Grand Prix. It had the 3.1 engine, same as base F-bodies.... It would read super high sometimes, peg out, but a few times, it would read like a normal gage. Before I went to synthetic 10W30, it would peter out to next-to-nothing, light the idiot lihgt, the whole nine yards. Synthetic fixed the problem... Shrug. Old car, don't own it anymore...