Something like that. I recently got my oil changed, and a couple of days after the oil pressure dropped. I brought it back to the place and they said it was most likely the oil pressure sender switch if I remember correctly. My oil pressure is irregularly low. I've got an 89 lo3. It was usually between 30 and 50, but now it's maxed out at 30. When I turn the key to ignition the guage shoots over past 60 until I start it. When I'm at a stop light the rpm's drop and after the car heats up, the oil pressure drops to 0, like the guage dies. When I have the AC on, the pressure drops quicker, and I have to rev the engine up to get the oil pressure back up. What's wrong with my car exactly? I could use an answer quickly, because it's a pain in the *** to have to put the car in neutral at every stop light.

 

It could be your sending unit your guage or the pick up in the pan is gumed up how many miles are on you motor.

 

107,xxx Anyone had the same problem?

 

I have the same problem, it seems to fix after oil changes but returns to that same problem after awhile. After oil change pressure will be 60 cruising 30 idle, now it barely will reach 30 cruising. I have an 88' 305 tpi. 176,000 miles on it, just drove from cali to NC and it's still running fine, except for this pressure problem.

 

This is a real pain in the ***, but I can replace anything that's busted. I just don't know what's causing this, and I don't have the time to dismantle everything related to the oil pressure right now.

 

If your really worried about it you can go to the auto pts. store like I did and get you a cheap direct oil pressure gauge and install it. There should be a small plug just below the intake manifold on the front of your block where you can run the line too. I had the same problem, looked at the gauge one day and crapped my pants when I saw 0 oil pressure. I went straight to the pts. store, installed the gauge, and walla! 40 lbs. at idle. The gauge is 1/5th the price of the factory elec. sending unit, and you get instant oil pressure readings, and you won't have to remove the stock unit w/the switch that will run your fuel pump if your fuel pump relay ever quit's. My car has 148K on it!

 

I wanna keep the original guage in working order. How do I replace it? I haven't climbed under there, but I assume it's right above the oil filter. Does anybody know the how to on this? I didn't find anything in the Chilton's. Do I have to drain the oil? Do I just take it out with a pair of pliers? How do I put it back in?

 

First, you have to figure out if you have an "oil pressure sending unit and switch" combination, or a seperate sending unit and an oil pressure switch.
If you have a seperate oil sending unit, it will be beside the distrubutor on the back of the block and will be a PITA to change in the driveway! That is how my 88 is setup but I hear GM changed to a combo unit sometime after 88. If you have the combo unit, your in luck and it should be easier. You don't have to drain the oil, and the unit is easy to get at being just above the oil filter.
On my 88 the sending unit is beside the dist. and the switch is just above the filter. The switch is responsible for telling the computer that there is oil pressure and has nothing to do with the oil pressure gauge. It's job is to allow the fuel pump to run if the fuel pump relay ever quits. The combo unit does both jobs.
So make sure your replacing the right unit.

 

I wouldn't be surprised if this oil change place put in 5w-30, since that's what the factory oil cap says. An older motor with over 100K will usually take a thicker, like a 10w-30 or 10w-40. For kicks, have them change the oil again with 10w-40 and see if your pressure is back up.

 

It doesn't matter what wt. oil you have, the oil pressure is regulated by the relief valve in the oil pump. You could fill it up with water and it would still pump 30 or 40 lbs. of pressure (not for very long though!). The fact that his gauge moves at all say's that it's capable of working. I really think his sending unit is worn out.

 

I just looked down at the sender/switch location, and it looks like a metal housing surrounds a unit right above oil filter. I've seen the picture of the sender/switch on cskauto.com and it looks like a small sensor the same size as the temp sensor. The unit above the oil filter looks to be larger than the o2 sensor. Is teh sender/switch inside the metal housing? Am I looking at the right piece?