Ok guys here'* one for ya: I have a 1995 Bonneville SE with about 76k miles on it. I've recently noticed that whenever the engine idles the oil pressure gauge reads very low (just over the red warning zone) and when the car is in drive and I am stopped at a light for example (braking while the engine is running and in gear) the pressure gage reads even lower and the warning lights/alarms go off. Once I hit the accelerator a little and the RPMs go up just a bit the pressure goes back up and the lights/alarms go off, but as soon as i stop giving it gass and the engine goes back to idle, the oil pressure drops to just above the warning zone again. The oil level in the engine is good (Ive checked it multiple times) and there seems to be absolutely nothing else going wrong. Engine temp stays normal, sounds normal, no odors, etc etc.... My old man and I have a couple suspects in mind: 1. When the car was at a garage having some other work done, they also did an oil change and they might have put a lighter weight oil in (i.e. 5w30 instead of 10w30). or 2. An oil pump that is starting to show some age/wear. Anybody else have any insight into this occurrence??? Thanks for any help.

The experts will be here soon, but I would start with either checking the actual oil pressure or just replacing the sending unit (It'* pretty cheap). The 3800'* aren't known for weak oil systems and the oil weight change wouldn't effect it to that extreme.

thanks for the input.. I also forgot to mention that this only happens once the engine has totally warmed up for about 10 minutes. Whether or not that makes a diff. I dont know. Just thought i would mention it as well..

Yes in my car when I had 10w-30 the oil pressure gauge would stay higher, and now with 5w-30 the pressure gauge is a little lower but not to the red tho. Hmmm, yes you will get seg. from the pro'*.

teh sending unit is prob going

so how exactly would i go about manually testing the oil pressure myself just to verify that it is really fluctuating as much as the gage says? And where can I go about finding a new sending unit? How hard is it to replace?

Not hard; it just screws in. I have not done this replacement on a Bonneville, but usually you unscrew them via a line wrench or open-end wrench around the base of the sending unit, or via a special sending-unit socket that you can buy for a few bucks, depending on how easy it is to get at.

I hate to say this but unless the sending unit is obviously wet on the outside and/or leaking, your problem is more likely to be a failing oil pump than a bad sending unit. Going to a heavier weight of oil can stave off the inevitable for a short while, but not long.

Some engines, particularly Oldsmobiles, have a habit of eating their oil pressure idiot lights or sending units, but not Bonnevilles. On the other hand, you do need to verify correct oil pressure readings anyway before tearing the engine apart. Good luck.

wheres the sending unit located so that i can get a good look at it and see if it is indeed moist....

Alright.. I did a search of previous posts etc. and based on what a bunch of others have said it seems like the sending unit is the problem. What I have yet to find is a place where I can order one. Is this gonna have to be a "take it to the shop" fix?

if you have jacks or a hoist its not to hard. however it mightbe a into the shop if you dont have a place to lift your car up or dont wanna squeeze underneath