Oil light: Driving a car into the ground

[BigMoneyJim]

I have a '97 Lumina with a 3L V6. After a recent oil change my oil pressure light stayed on at idle. I spent some $$ to replace the oil pump and screen, but it didn't put the light out. Put some thicker oil (20w50) in, and now the light usually flickers at idle when the engine is hot but stays off while cool or not idling. The mechanic says the pressure is now right at the spec (minimum, I presume...17 lbs IIRC) at 1100 rpm, but there is no listed spec for idle.

I'm in a cash flow squeeze for a while, and I'm not sure if my job is stable past December. (It probably is.) But my cash and credit reserves are strained after several months of not working.

After tossing around a few ideas, I'm thinking of driving this car until the engine fails or until I can comfortably afford to replace it with what I want.

What I'm wondering now is how long might the thing last, and will I have some warning before it's not drivable? Anybody have an idea? I'm guessing it's the bearings wearing down.

 

[UncleHoney]

Did you try replacing the oil pressure switch?

UH

 

[haha]

Buy a cheap compression gauge and test your cylinders, or go to one of those electronic test lanes where for relatively small bucks you find out if your rings are ok, if perhaps the valves aren't seating correctly.

It may only be the sensor that turns on the light. This is usually a cheap replacement that you can do yourself. Or go into Shucks or Pep Boys or NAPA and get an aftermarket gauge that will give you pressure readout.

Overall, even if you have an idle problem you are not doing much damage at idle with hot oil, since lubrication demands are small under those conditions.

If pressure is low under load, you will possibly damage the main (crank) bearings. As this happens you will hear an engine rattle, especially on startup. Another serious symptom is a thunking knock when you are under load, as in hill climbing. None of these should be ignored, as they can stop you when it might not be safe.

Ha

 

[BOBOT]

Put some black tape over the light & keep driving. Ignore all grinding noises. Save the $$ for the new vehicle that is inevitable anyway. Be serene.

 

[FinanceDude]

Put some black tape over the light & keep driving. Ignore all grinding noises. Save the $$ for the new vehicle that is inevitable anyway. Be serene.

 

[Trek]

Pretty amazing a 97 Lumina still runs at all! If I were you, I'd buy a used folding bike and keep it in the trunk. Ignore the light and drive the car until it dies, saving your money all the while. When it does crap out, you can pedal home.

 

[JB]

I think Ha has it right. How many miles does the car have it it?
BTW, I still have my compression gauge. I use it on any used car I might buy.

My old Chrysler that went 300K on the orig. engine. For the last 50K or so the oil pressure was low at idle (had a gauge). I think the main bearings rattled a bit at startup too. The car died of other causes.

 

[Nords]

I'm in a cash flow squeeze for a while, and I'm not sure if my job is stable past December. (It probably is.) But my cash and credit reserves are strained after several months of not working.

Check the oil pressure sensor and the circuit that turns on the oil-pressure light. If it's not one of them then keep on driving while checking Craigslist for those bargain-basement desperate sellers. You can find a great used-car deal if you have the time to shop for it.

Or else you might end up having to save up for a bus pass...

 

[Texas Proud]

Pretty amazing a 97 Lumina still runs at all! If I were you, I'd buy a used folding bike and keep it in the trunk. Ignore the light and drive the car until it dies, saving your money all the while. When it does crap out, you can pedal home.

Whys that?? I have a 95 Monte Carlo with the 3.4 engine as my daily driver.. except for an cold idle problem that I have not taken it in for and a bad coolent level sensor it runs just great... now, I only have 80K miles on it... but still..

 

[Keim]

Heh-I can beat that. I have a 1976 Monte Carlo. Still going strong...
In my book anything in the 90's is still new!

Whys that?? I have a 95 Monte Carlo with the 3.4 engine as my daily driver.. except for an cold idle problem that I have not taken it in for and a bad coolent level sensor it runs just great... now, I only have 80K miles on it... but still..

 

[Telly]

After tossing around a few ideas, I'm thinking of driving this car until the engine fails or until I can comfortably afford to replace it with what I want.

What I'm wondering now is how long might the thing last, and will I have some warning before it's not drivable? Anybody have an idea? I'm guessing it's the bearings wearing down.

A rule of thumb for oil pressure is you would like to see a 10 PSI increase for every 1000 RPM increase in engine speed. Which still doesn't say anything about idle.

Idiot light oil pressure switches usually turn off at 5 - 7 PSI or so.

If running 20W50 in it gets it down to a flicker at idle, it may last a long time yet. If you live where it gets pretty cold in winter, 20W50 will cause you problems, too thick for cold start-up in winter. But it's a long time till winter comes around again!

Since you've had the oil pump changed, and the intake screen cleaned, increasing bearing tolerances are most likely the reason. I'm assuming you have a 3.1L engine. You might want to post on some Chevy forum somewhere, and see what the more seasoned board members who actually work on cars say there. You would need to lurk for a while to figure out who really knows, and who just repeats. I mention a Chevy forum, because I have a very vague remembrance of some particular condition with the GM 3.1L for some run of years. Or maybe I'm thinking of something else...

When oil pressure starts to get too low to support a continuous oil film in bearings under all conditions, it will start to make noise. And the noise will increase over time. Most likely you will have a pretty good warning interval before it actually dies. The noise can get pretty horrible, can't miss it.

Cylinder wall/ piston ring wear will increase oil consumption, it will not decrease oil pressure.

 

[Telly]

I After a recent oil change my oil pressure light stayed on at idle.

I just re-read your post and caught this part about recent oil change. Was the correct part number oil filter put on?

If there is any doubt at all, check your owners manual and use the exact AC Delco filter specified.

I hope you did not have an "engine flush" done somewhere! "Yes, for just $69.95 we'll run some solvent through your engine and destroy it for you!"

 

[BigMoneyJim]

Thanks for the responses. It sounds like I can run this thing into the ground and have enough warning to know when I must buy another car.

As far as the questions about the light and pressure sender, the mechanic hooked up their gauge and gave the the 17 psi reading.

Interesting idea on the bike, but maybe it's time for a roadside service / towing plan.

I live in North Texas now, so cold weather isn't much of a concern.

I've always thought it was a 3.0 L engine, but apparently it's a 3.1 L engine after all.

I'll double-check the oil filter, but I had the oil changed again to cover any filter or oil issues. But it's worth checking myself.

 

[bright eyed]

Put some black tape over the light & keep driving. Ignore all grinding noises. Save the $$ for the new vehicle that is inevitable anyway. Be serene.

OMG! my dad does that in his car, thought he was the only one...

 

[TromboneAl]

Your post highlights the problem of driving a car into the ground: poor reliability towards the end. That is, you want to get every ounce of value out of the car, but you don't want to end up stranded on a dark, rainy highway at 1 AM.

 

[Gumby]

Your post highlights the problem of driving a car into the ground: poor reliability towards the end. That is, you want to get every ounce of value out of the car, but you don't want to end up stranded on a dark, rainy highway at 1 AM.

But that's when you meet all the great guys with chainsaws and hockey masks.

 

[Ed_The_Gypsy]

STP.

 

[cute fuzzy bunny]

Jim - any smoke, leaks or oil in the transmission fluid or coolant? Using how much oil per thousand miles?

If no to all of those, its probably a bad oil pressure sensor. Not much to worry about if you keep an eye on the oil level.

I know a mechanic who's made a lot of money replacing GM v6's...

 

[thefed]

did nyou ever have an intakre problem on that caR? im pretty sure its the 3.1 that is notorius for intake problems starting as low as 50k miles


just wondering

 

[Sam]

If no to all of those, its probably a bad oil pressure sensor. Not much to worry about if you keep an eye on the oil level.

The oild pressure sensor is cheap and relatively simple to replace. That's the first thing I'd do. Good luck.

 

[FinanceDude]

did nyou ever have an intakre problem on that caR? im pretty sure its the 3.1 that is notorius for intake problems starting as low as 50k miles
just wondering

The 3.1 had some issues, depending on the year. I had a Grand Prix with the 3100 motor, which was basically the 3800 block with smaller displacement. The car is still running around my nieghborhood with 189K on it, sold it to a noeghbor's kid.......

 

[Andre1969]

I've had two cars that would do that same thing, having the oil light flicker at idle, when fully warmed up. The first was a 1967 Pontiac Catalina. It only came from the factory with an idiot light for the oil pressure, but there was an aftermarket gauge hooked up to it. Once it was fully warmed up, it would idle REALLY low, and the light would flicker. I think it would do it around 15 psi. Pontiacs back then were known for idling low, but I think someone messed around with the idle on this one. I bumped up the idle a bit, and my mechanic recommended running 20W50 oil in it, and never had a problem since.

My 2000 Intrepid started doing the same thing about 2 1/2 years ago. It turns out there was a TSB on it. There was some kind of issue where the sensor can get too hot and trigger a false reading. Usually at idle, fully warmed up, where it's going to be hot with no airflow to dissipate the heat. The scary thing about the Intrepid though is that it actually acted like there was a real problem. If I put it in neutral and tapped the gas to boost the revs, the oil light would turn off.

I'd say if it's only doing it at idle, you might be able to get away with putting the car in neutral when you're stopped at a traffic light or similar situation. That'll take the load of the transaxle off the engine, and it'll rev up just a bit. Maybe enough to make the light go away.

 

[Nords]

That is, you want to get every ounce of value out of the car, but you don't want to end up stranded on a dark, rainy highway at 1 AM.

You also want to have a month to go shopping for a new car, time to take care of the title & tags, and time to arrange the artificial-reef permits for disposal of the old vehicle...

 

[USK Coastie]

A mechanics rule of thumb for engines is 10 psi per 1000 RPM. This is the minimum requirement for proper lubrication of the engine. Since you said the engine was delivering 17 psi at 1100 RPM probably no big deal. If you're still concerned I vote change the oil pressure sending unit, go to 20-50w oil and add STP to the oil. If you live in a moderate to warm climate the car should run fine. If you live in a cold climate use 15-40w in the winter months otherwise additional engine wear will occur during start up.

 

[MasterBlaster]

It sounds like I can run this thing into the ground and have enough warning to know when I must buy another car.

There is no guaranty that the engine will fail gracefully. A major bearing could go or you could throw a rod and have catastrophic failure.

I had a fun and event filled time years ago as an engine quit on me while I was doing 70 or so. But that's another story.