: Oil pressure dummy light flickers...

08-17-09, 04:09 PM
I have a 1996 Cadillac DeVille with about 190k miles on it. The oil pressure light has been flickering for awhile. And it actually took me awhile to even tell which light was coming on, because as soon as it was in my peripheral vision I would look and then it would be gone - like it was playing games with me.

I had some problems after changing the starter (thanks again to the guys who commented here http://www.cadillacforums.com/forums/northstar-performance-technical-discussion/174909-white-smoke-after-changing-starter-removing.html#post1943672).

After I got that all straight, I took it for a drive after it sat for about a week and 15 minutes into the drive it tells me to turn off the engine due to low oil pressure. So, I do. I check the oil level. It is low, but still within the acceptable range. I go ahead and fill it to the top of the range and start it back up. After driving for about 10 minutes, the light starts flickering.

As far as I can tell, it only flickers when the RPMs are low 625-750. If I even touch the gas the light goes off.

Any ideas on how I should diagnose and tackle this problem would be greatly appreciated. I am also pretty inexperienced, but I live close enough to ride my bike to work - so if it takes a while to get right, I don't need my car.

08-17-09, 05:43 PM
Some have had trouble with the oil pressure sending unit (switch, sensor) which is screwed into the top of the oil filter adapter on the front side of the engine (4.6L Northstar ???) Find a new ACDelco unit in www.rockauto.com or call Luke in parts at Lindsay Cadillac, over there >>>>>>>

Either you or a local Mom&Pop shop can change the unit in a half hour. Make sure you're using the recommended multigrade oil (10W-30) for your engine, and consider shifting to a Shell Rotella, Pennzoil Long Life, or CHEVRON Delo fleet/marine oil in the same viscosity rating. Why ?? These oils have a higher load anti-scuff additive package which is perfect for your flat tappet cam followers.

You should be able to carry the oil level at just about halfway up the dipstick hashmark. Any higher leads to excessive oil consumption. Ask your GM dealer Service Writer for the Technical Service Bulletin on this.....he'll/she'll look at you like you're crazy.

08-17-09, 08:43 PM
I have noticed the same thing from time to time at idle in drive with my 97 Deville 82,000 m , I thought it was just idling a little too low and causing the light to activate from time to time.

08-17-09, 09:33 PM
Either the oil pressure switch is defective, or you do have low oil pressure due to engine wear, which is entirely possible at 190K. Change the switch first, if you still have the issue, consider a slightly higher viscosity oil that won't get squeezed out of the bearing to crankshaft area so readily. I'm putting my money on the pressure switch - it's a little hard to get at - I had to remove a motor mount stud form the block for access on my '97 ETC. Be careful you do not cross thread when installing the new switch, and the stud if you need to remove it. The stud requires a special socket - I think they are called "e" sockets it's like a female torx

08-18-09, 11:48 AM
Thanks, I will check into the oil pressure switch and update y'all when I get it changed out. Although it could be awhile, my job is about to kick into high gear for a few months.

While we are on the topic of oil. I use Pennzoil High Mileage Vehicle 10W-30. Is there any pressing reasons why I should switch? I am no oil brand fanatic and have no loyalties, but since submariner409 made some suggestions - I was wondering about the wisdom of my choice.

08-18-09, 04:27 PM
Pennzoil High Mileage is another of the high-additive package oils. Perfectly fine.

( :sneaky: I'm prejudiced: I use Pennzoil 5W-30 Platinum synthetic - and a WIX 51522 filter - in my STS.)