: Weird oil pressure/stop engine light thing



ReagansRollsRoyce
04-29-07, 08:42 PM
An odd thing is happening with my Stop Engine/Oil Pressure light.

Facts:

Car is running Valvoline synthetic 5W-30

If the car is driven around at below highway speeds, there is no problem, no matter how long it is driven.

If the car is driven for more than 10-15 minutes on the highway, after you get off the highway and come to a stop, say at the end of the exit ramp, the stop engine/oil pressure light comes on. AS SOON AS the gas is pressed, it goes off.

The light comes on thereafter whenever the car is at a stop until you

a)shift it into park (it goes back on if you shift into drive)
b) turn it off and let it sit for half an hour

The light is never on when the car is in motion above 3 mph. As you slow down towards zero it starts to flicker, then stays on solidly at the stop.

The light also comes on even without going on the highway if you are at a stop light and turn the air conditioner on. If you turn the a/c back off, the light immediately goes off.

Other facts:

Car has a very slight oil leak (one tiny spot per week, perhaps)
Checked oil, it's still on Full
Oil is changed regularly
Car is operating normally, getting good highway mileage, engine is smooth.


Any idea what is going on? Is this a circuitry thing?

jayoldschool
04-29-07, 08:52 PM
An odd thing is happening with my Stop Engine/Oil Pressure light.


Any idea what is going on? Is this a circuitry thing?

Yes, your engine is getting worn. Get that thin oil out of there, and put in some 10w40 (min) ASAP. Your main bearings are being starved when that light comes on...

Wheelman322
04-29-07, 09:20 PM
Yes, your engine is getting worn. Get that thin oil out of there, and put in some 10w40 (min) ASAP. Your main bearings are being starved when that light comes on...

I'm inclined to agree. One Question...What mileage was the car at when you started running synthetic? Sometimes synthetic does more harm than good in an older high mileage motor.

ReagansRollsRoyce
04-29-07, 09:22 PM
Probably 85K, I now have 112K....think I'll get some regular 10W in there tomorrow...sound good?

Old Fleetwood
04-29-07, 10:31 PM
AMEN to the 4th power!:thumbsup:

jayoldschool
04-30-07, 08:06 AM
Probably 85K, I now have 112K....think I'll get some regular 10W in there tomorrow...sound good?

No. The first number is the cold flow. It will only be thicker at start up. You need something that is thicker when it is hot. Minimum 10w40. Personally, I would use 15w50 for the summer. BTW, my old 87 Caprice with the 307 Olds did this after about 100k, so I know what you are going through.

ReagansRollsRoyce
04-30-07, 09:56 AM
Done..will experiment on the next commute and report back.

ReagansRollsRoyce
04-30-07, 11:23 AM
Jay, thanks a lot!

10w40 was all that was available so I had that put in.

It seems to have stopped the problem.

So everything in that department should be okay, I guess, unless the bearings were already ruined by the thin-ness of the 5w40.

Wasn't a problem until recently, as with your Caprice.

jayoldschool
04-30-07, 02:01 PM
Jay, thanks a lot!

10w40 was all that was available so I had that put in.

It seems to have stopped the problem.

So everything in that department should be okay, I guess, unless the bearings were already ruined by the thin-ness of the 5w40.

Wasn't a problem until recently, as with your Caprice.

Glad to help! This is a good forum.

I wouldn't worry about the bearings - they are just getting worn and the tolerances are opening up. If they were really bad, it would knock.

JTraik
04-30-07, 03:45 PM
What kind of noise does your engine make when you start it up after a cold night? When bearings are starting to wear down they will make a wahh...wahh...wahh...wahh sound for a time determined by how much they are worn down. If it sounds normal and consistent then your problem is gunked up passages or the pump is starting to show its age.

As others have suggested... get rid of the SYNTHETIC light weight and replace with DINO heavy weight. If you want to stay synthetic you are prone to leaking and if you properly maintain your car you will need to replace filters before oil changes with synthetic... thats why its just better to stick with dino so they can be done together as a matter of convenience.

Motorboat
04-30-07, 04:34 PM
A little background. I owned a fleet of over 100 tractor/trailer combinations. During that time I tried many oils. Long story shortened. Never break in an engine with synthetic. In spite of what Corvette and BMW recommend, these motors and others were worn in with Dino oil.

Synthetic will leak where conventional oils will not. Unless you are willing to significantly extend drain intervals, your wasting your money on synthetics.
One advantage is that the motor will start easier in subzero weather. Slight and I mean very slight horsepower gains are realized.

In spite of testing synthec oils on trucks in groups of 25, there where no measurable savings to be realized. It should be noted that these trucks were on a five year lifecycle (depreciation) and many other factors were taken into consideration.

If you are a Greenfreak go synthetic because it is manufactured and therefore not depleting our oil reserves.

In summary; if I had a keeper I would do the following. Break it in on Dino oil, (my choice is Rotella) to about 1500 miles then switch to synthetic (my choice is Castrol). Change oil and filter at 8000 miles and relax.

cadillac_al
04-30-07, 07:15 PM
I think when that engine was new, the tolerances were too loose for 5w30. I like 15-40 fleet oil in any v8 with over 100,000 miles. I might re-think that for a northstar since they are built with tighter tolerances.

ReagansRollsRoyce
04-30-07, 08:58 PM
Glad to help! This is a good forum.

I wouldn't worry about the bearings - they are just getting worn and the tolerances are opening up. If they were really bad, it would knock.

Yeah no knocking or whining or anything odd right now. As soon as I put in the 10w-40 I took it on a 20 mile highway trip and when I got off, no light. A/c didn't make it go on either.

If it did start knocking, would it do so at all speeds, or just certain speeds. And would it be more of a low thud or a hammer like whacking noise.

Just want to know for future reference.

And yes, I have junked synthetic and am back to regular old oil. I had continued to use 5w-30 only because the manual said to do so.