[rhudeboye]

Took a friend for a ride in the 68 yesterday. The car has been sitting for about a week. I went down the street, turned the corner and the check oil light came on. This is the first time I have seen this light. I pulled over after about 1/4 mile and checked the oil level. All looked well. I started the engine and there it was again. We stopped a CVS a block away to get some drinks and I decided to cut the ride short. Come back out of CVS, start the car and no light. Drive home shut it off and restart it a bit later, no light. I drove it to work today as well and no light.

Q-
1. Does that light only trip when the oil level is low or would a failed pump, coolers etc play trip the light?
2. Could the cold temps (avg 20 degrees in MD) we've been having lately play a role?
Meaning did the oil thickened and have to warm up to optimal temps to circulate properly.

I last changed with AMSOIL European Car Formula 100% Synthetic 5W-40

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[968gene]

was the car parked on a hill for the previous week?

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[rhudeboye]

Nope, in a leveled garage.

But it did sit at an angle in the driveway for about 4 hours as I pulled it out and sprayed it down earlier that day.

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[94SilverCab]

I've had similar gremlin in the past...so far, nothing to worry about. It starts functioning normally again in a short time.

EDIT: Once, when it didn't self correct it was a vaccuum hose disconnected at the firewall.

Jay

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[Chris Vais]

If you cold start the car, back it out of the garage onto a sloped surface and shut it off before the engine is fully warmed up, you may see a check oil light when you restart the car. This is especially true if your oil level was say a 1/2 quart down. This occurs because if you cold start an engine and immediately shut it down it takes a long time for the cold oil to drain back into the oil sump. If the cold oil is slow to return to the sump, it may not be sufficient to to contact the oil level sending unit, hence the warning light.

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[Fox944]

Chris Vais is spot on. Also Whenever i park on a steap uphilld, my oil light will com on when i restart the car (regardless of oil level).

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[Kim]

The light will come on when the oil level is down even 1/4 - 1/2 litre. There is a circuit that prevents the light from being shut off unless the car has been off for 2 minutes. That prevents one from "ignoring" it. When the car is cold that light will come on a lot if you shut it off and restart since the oil doesn't drain back fast enough. When the car is hot the oil will drain back faster and the light will come on on a quick restart only when you really need oil. But anytime it comes on you probably need a bit of oil to be at the max level. If the sensor fails, which mine did, the light will come on even with just a teaspoon less than a full reservoir and, at that point, the sender needs to be replaced.

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[rhudeboye]

Thanks all. Thats one more peice of the car I understand a bit better.

Chris- your mention of backing down a driveway and shutting it off is exactly what happen earlier in the day when I washed it off.

FYI I did end up adding 1/4 qt even though the dip stick level was dead center on a cold engine.

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[hryden]

I have this issue as well, but have not been able to cure it yet. My check oil light started out intermittently coming on with slightest change in oil level. It would usually turn itself off after turning the car off and letting it sit for a few minutes. Eventually, it stayed on constantly (it's still on) even when the oil level is right.

I assumed (bad idea) it was the sending unit, so after checking the wiring for damage I went ahead and replaced it. That did not solve the problem, so now the light is still always on. A Porsche mechanic told me that he thought it was the circuit board in the instrument panel that had gone bad and it needed to be replaced to solve this problem. I had never heard of this before, but checked the schematics. There is indeed a replaceable circuit board in the instrument panel.

Anyone had this happen or have any ideas on how to fix it? Or is this circuit board the answer?

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[DaveN]

I doubt it's the cct board in the instrument cluster. This is just a flexibly PCB and unless you have had salt - moisture in there for years that should not have corroded or magically shorted just one path to VCC. If one of the 3 connectors that attaches to this PCB were intermittent I would think the light would always be out not on due to lack of sender voltage or a path to GND.

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[stewhatch]

FWIW I have always been under the impression that synthetic oil maintains it's viscosity throughout it's assigned temperature range, regardless of outside temps. I always thought that was (one of) the advantages of using synthetic oil. Do I have this right?

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[Kim]

I think that the difference between conventional oils and synthetic oils is more in the sizes of the various molecules and additives - synthetic oil particles and additives are very uniform in size and do not change much with heat or pressure. Conventional oils have a variety of sizes of components and also tend to change chemistry due to heat and pressure. There is likely no shortage of info describing the differences.

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