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Discussion Starter · #1 ·
When waiting at the Tunnel in Calais, stationary with the engine running after a 250-mile drive, my oil light (red oilcan) came on and stayed on. I had already been standing for say 20 minutes at passport control, mainly with the engine running, but I had turned it off a couple of times.

When I drove off the far side, the oil light did not come on, but I stopped at the petrol station and poured more oil in anyway. The oil looks like clean yellowy oil and the coolant (which has remained full) is like coolant with that red stuff in it. The car is driving well. So I don't suspect HGF. (If I had I would not have driven it further).

The dipstick now shows full.

The light is now off, though I wasn't sure if it flickered as I drove the car into the garage on a warm engine having stopped the engine after a long run ending with a gentle drive.

Could this be something to do with running the engine when stationary after a long run? I normally do...
 

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Did you check oil level before you set off ?. It may of been low before you set off and with maximum suction on idle/tickover for the length of time you were stood still it could of sucked that little bit more into the inlet tract as they do on tickover and taken it below minimum limit for oil pressure.
 

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Discussion Starter · #4 ·
Did you check oil level before you set off ?. It may of been low before you set off and with maximum suction on idle/tickover for the length of time you were stood still it could of sucked that little bit more into the inlet tract as they do on tickover and taken it below minimum limit for oil pressure.
I had checked it 350 miles earlier and it had been good (looked full after wiping) which was the strange thing. It was parked at an angle in France so I didn't check it there.

Strangely enough, although my engine has always leaked drips of oil now and then, it has never needed regular (any!) topping up, unlike my 420 Tourer.

Has it had a new oil filter fitted recently?
It's been serviced to schedule and Dr Dave did the 7-year service in July.
 

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Running the engine after a run shouldn't make the oil pressure light come on (I do this with mine and have never had a problem-there I've jinxed it); what grade of oil is the car using?

I wonder whether for the cost if it's worth doing an oil & filter change to ensure there's no blockage in the filter. After this-I would guess the next step would be to carry out an oil pressure test to ensure the engine is making good pressure.
 

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It sounds like it could be an engine temperature thing. Oil gets thinner as it gets hotter - I presume that would cause the pressure to fall (but it's not something I've ever thought about).

If the engine was hot, the oil a thin grade and the pressure sensor slightly out of spec, these might combine to create a red light. Of course, if oil pressure gauges were still standard, it would be much easier to tell if there was a real problem.
 

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Usually a car will have an oil pressure within the crank when warm of about 40psi, the low oil pressure light will light up when the pressure is at about 7psi, usually indicating that the car has had it. this doesnt seem to be the case, I would guess that the oil pressure switch is failing or the wiring going to it is, another possible problem could be the oil pump its self, there is a regulating valve within it, if it was stuck open then the cranks pressure would be abnormally low triggering the low oil pressure switch.

If i was you i would take it to a garage and get them to check the engines oil pressure by sticking a pressure gauge into the oil pressure switches housing, this will tell you whether its just the switch or if there is a more serious problem.
 

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Discussion Starter · #9 ·
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If i was you i would take it to a garage and get them to check the engines oil pressure by sticking a pressure gauge into the oil pressure switches housing, this will tell you whether its just the switch or if there is a more serious problem.
OK. I use Mobil 1 0W-30 so it is a thin grade to start with.
 

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I kinda doubt if the oil viscosity would affect the oil pressure as there is a regulator within the oil pump its self, but that is pretty thin oil, i use 5w40 synthetic and never have leaks apart from the usual film within the inlet manifold. The best bet would be to ask someone at a garage to check the oil pressure when the car is at operating temperature. it is normal for oil pressure to lower quite a bit from cold to warm, up to 50% from what ive seen
 

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Strangely enough, although my engine has always leaked drips of oil now and then, it has never needed regular (any!) topping up, unlike my 420 Tourer.

And in this statement could well lie your answer.............................


Leaking oil pressure switch have had this on more than one occasion..the switch starts to leak between the plastic dome and the metal nut and this can cause a drop in pressure inside the switch..........and the light comes on at low revs
 

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OK. I use Mobil 1 0W-30 so it is a thin grade to start with.
Might be worth changing to 5w40 or 10w40 and replacing the oil filter-it's worth a try before going to the expense of professional oil pressure tests. As said already it's also worth a look at the oil pressure switch-if this is leaking it can cause the light to flicker on.
 

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It wouldn't be worth changing the oil & filter - as these items haven't done much mileage.

I can't see the engine having consumed enough oil to bring it below the min level and beyond, enough to bring the low pressure light on.

My money would be on a faulty/wet oil pressure switch or a chafed wire to it.
 

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Discussion Starter · #16 ·
It wouldn't be worth changing the oil & filter - as these items haven't done much mileage.

I can't see the engine having consumed enough oil to bring it below the min level and beyond, enough to bring the low pressure light on.

My money would be on a faulty/wet oil pressure switch or a chafed wire to it.
Thanks for the tip - the light flickered on again today, then off, at idle, although I have filled extra oil in.
 

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What level is the oil at on the dipstick?

Be aware not to push the dipstick fully home to check the level - push it down to the first o ring, wait and then fully insert it and then take a reading.
 
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