Hello,
First time here, so let's give it a try. The symptoms-Father in law has a '97 Deville that the oil sensor light on the display screen (oil can)flashes when the car reaches 212 degrees F or higher(oil is new, the right kind of oil, and isnot low). We have change anoil sensor underneath of the car which hebelieved to be the problem, it did not help. Only once has it been a steady light (not flashing)which was on a 100 degree plus day. I believe the operating temp is supposed to be 212F. The car reached a temp of 222F on a very hot day, an auditory indicator noise from the dashcame on and the digital read out said low oil pressure. We now guess that when the car heats up above the operating temp that the oil loses enough of it's viscosity to give an indication of low oil pressure (this is a shot in the dark guess by a couple of amatures). Could it be the water pump is going out? Could it be the thermostat is not working properly? Could it be the wrong anti-freeze? Would the outside temp make that much of a difference?

Put simply - the car slightly overheats, and on the digital dash the oil can flashes some of the time. One time, it overheated more than it had done in the past and a bing/ping/ding indicator noise came from the dash with the digital reading oflow oil pressure.

Thank you for your expertise advise and your time.

Greg Eccleston

 

First of all how many miles? whens the last time there was a coolant system flush? and im assuming it has dex-cool still in it?

 

I have the exact same problem on my 96 DeVille with only 39k miles. What is the normal operating temperature range? Mine has never passed 215 even when sitting in heavy traffic but the oil pressure light will flicker even as low as 200 after the motor has warmed up. It only happens at idle. There are no other indications that something is wrong. The oil level is tippy top on the dip stick marker but does not seem to be related to the oil level or freshness. I haven't thought of the coolant as the problem simply because the temps I see do not seem too high.

Not sure what to check next.

 

When your oil light comes on the oil pressure may be low because of a worn or broken oil pump, a plugged oil pickup screen in the engine’s crankcase, possibly a plugged oil filter and in extreme cases excessive bearing wear or a blown head gasket. Oil pressure may be fine but the oil pressure sending unit could have failed. Further diagnosis will be required to determine what’s wrong.

In all likelihood your vehicle will overheat or show increased engine temperature. In the Northstar engine temperatures of 220 degrees areconsidered normal. Make sureyou are certain there is sufficient oil and that oil is circulating. If you check your oil and it has a milky color, this could be a blown head gasket that has allowed water to get into your oil.

 

What doesn't add up for me is the motor is less than 40k miles and I met the (older couple) previous owners, have all the records, car fax report is clean and matches their records ... I drive it very reasonably with a light touch, oil is clean, full, right color, temps run 196-205 most of the time but never seen over 215 in hot rush hour traffic, yet the light still comes on. I hope its just a bad sensor, but I am not sure what other symptoms to be worried about. I am going to have the oil changed and sensor again just to make sure.

 

I agree, not enough miles to have serious internal problemsbut it could have a clogged pickup or bad pump none the less. I don't think your temperatures are a worry either, just mentioned all possibilities. If you put in another sensor and it still comes on, what about a heavier weight oil, sound like you live somewhere pretty warm.

 

Yes, it can get pretty hot here in Texas. I if after changing the sensor and oil and it still comes on, I will try a heavier oil. I just talked to a Northstar mechanic last night and he said he had never heard of this happening ... apparently it is not very common. Hopefully it is just a glitch ... will follow up.