Oil mystery.

[Kruzen]

I know for a fact that my car is leaking oil (whole front underbody is damn saturated with it)

Everytime i change the oil and put in another 4.5qt, after i've driven about 2000 miles (almost like clockwork, actually) my ENGINE OIL checklight comes on.

usually this means i'm about a half to .76 quarts short, so i toss it in, engine light goes away, and all is good.

So last night i was coming up on 3,066 miles on the current oil change, i usually replace it sooner. I had already added more oil 1,066 miles ago when the light popped on. Well i was driving home and the light came on again. I was about 2 minutes from my house, normally i would've stopped and put more oil in (usually keep a spare qt in my trunk) but it popped open earlier that week and leaked in my trunk :-/ so i just drove home and figured i'd throw some more oil in in the morning.

So the next morning i go out, check dipstick, sure enough its about the middle line, needs more oil.

So i toss in about .75 qt as usual just to tide me over and keep the engine happy until after i got back from my test that i was leaving for, to change my oil when i got home.

I put the .75 qt in.. wait a minute, go back and turn the car on to acc.. hmm engine oil light is still on.. ? weird.

*check dipstick* .. still not quite full. so i added another half qt..

*check light..*

still not happy? wtf?

so i added the rest of that bottle (another half qt)

by this time the dipstick was reading that i was slightly OVER the upper line.. fair enough i said to myself, i'm changing it in two hours anyway.

So i hop in the car and to my amazement, the engine oil light is STILL ON.

i turn on the car and let it run for a minute ,rev it a few times (which was rather unsettling, didn't sound quite normal, but its been really cold lately and my car sits outside so i blamed it mostly on that)

Got out of the car after a minute, check the dipstick, couldn't get anywhere near an accurate reading, one time i put it in and it came out with the line a 1/4 inch past the upper bar, next time i put it in and the line was 1/4 from the lower bar.. results were wacky.

So i said to myself "fuck it, i just added a quart and a half to it, and i know it had at least 2-3.5qt's in there already, i think the computers playing retarded or i got a bad sensor overnight"

So i drive to class, once the car warms up the revving problems settle, go and take my test, come back and start the car, and after it sitting in the parking lot for an hour, the engine oil light mysteriously gone.

Its a mystery to me what the hell is going on and why it was reading as not enough oil when the car was cold, but after running for 20 minutes and sitting for an hour, suddenly its got plenty.

sidenote: when i got home i put the car up on jacks and drained all of the oil for 6 hours or so while playing half life 2, swapped out the filter, added another 4.5qt of castrol gtx 20w50, and she's running fine again.

Additionally, is there anything i can do about locating my oil leak? everything is so saturated down there i can't tell what it is, i spent an hour cleaning off my oil pan a couple of months ago to see if any oil was running down it, but its still shiny silver.

one last tiddy, at what level ont he dipstick is the oil sensor supposed to report being low?

[Madhatter]

I would put money on a dying oil pump if it is playing games like that. The oil can read full on the dipstick and the light can come on, it's due to oil pressure and not actual oil volume. i would take out the sender and screw in a pressure gauge and see what sort of pressure you are getting.

From memory at idle it is 0.5 - 2.0 bar
at high revs it is 5.0-6.0 bar

If you are quite a way outside those figures you have something really wrong, either a physical blockage (check the oil pickup in the sump) or as i said the pump is faulty. The fluctuations on the dip stick sound like it is having problems circulating the oi, not a good sign if you value the health of your engine.

Edit: As for the oil leak, degrease the entire engine, anywhere there is oil, you cant go looking for oil leaks without the area being clean.

[trent]

I would put money on a dying oil pump if it is playing games like that. The oil can read full on the dipstick and the light can come on, it's due to oil pressure and not actual oil volume. i would take out the sender and screw in a pressure gauge and see what sort of pressure you are getting.

From memory at idle it is 0.5 - 2.0 bar
at high revs it is 5.0-6.0 bar

If you are quite a way outside those figures you have something really wrong, either a physical blockage (check the oil pickup in the sump) or as i said the pump is faulty. The fluctuations on the dip stick sound like it is having problems circulating the oi, not a good sign if you value the health of your engine.

Edit: As for the oil leak, degrease the entire engine, anywhere there is oil, you cant go looking for oil leaks without the area being clean.

Hmm...I think he means the engine oil CHECK light on the overhead check panel. This does just have a level sensor in the oil pan. I don't think he means the oil PRESSURE light on the cluster.

[parkerbink]

My dash oil dummy light comes on when the dipstick level shows 1/4 below full. I want a real gauge that shows actual pressure (as well as a real voltage gauge) shame on BMW for not putting those in a car as expensive as this that they call the "Ultimate Driving Machine"

[Fred]

Hmm...I think he means the engine oil CHECK light on the overhead check panel. This does just have a level sensor in the oil pan. I don't think he means the oil PRESSURE light on the cluster.

Yup, sounds like the oil level sensor.

[Brew]

What the weather like over there? If it gets below 40 or so overnight, I wouldn't dare run that thick of an oil. That could also cause some oil pressure issues. Go for at least a 10w-40.

[Kruzen]

What the weather like over there? If it gets below 40 or so overnight, I wouldn't dare run that thick of an oil. That could also cause some oil pressure issues. Go for at least a 10w-40.

It gets pretty cold overnight, sometimes under 40, but the usual weather is around 50-55 degrees during the winter's here.

I may be abel to get my car into the garage for the winter and out of the outside.

http://www.weather.com/weather/local/98335?lswe=98335&lwsa=WeatherLocalUndeclared

[Kruzen]

I would put money on a dying oil pump if it is playing games like that. The oil can read full on the dipstick and the light can come on, it's due to oil pressure and not actual oil volume. i would take out the sender and screw in a pressure gauge and see what sort of pressure you are getting.

From memory at idle it is 0.5 - 2.0 bar
at high revs it is 5.0-6.0 bar

If you are quite a way outside those figures you have something really wrong, either a physical blockage (check the oil pickup in the sump) or as i said the pump is faulty. The fluctuations on the dip stick sound like it is having problems circulating the oi, not a good sign if you value the health of your engine.

Edit: As for the oil leak, degrease the entire engine, anywhere there is oil, you cant go looking for oil leaks without the area being clean.

Hmm...I think he means the engine oil CHECK light on the overhead check panel. This does just have a level sensor in the oil pan. I don't think he means the oil PRESSURE light on the cluster.

correct, i'm not talking about the one on the dash, i'm talking on the overhead check panel.

[mikeedler]

mine does the same sometimes. It just takes a while for the oil to get to the section of the oilpan where the level sensor is. not a big problem. Mine was "eating" alot of oil too. I replaced the "doghouse gakets" on the front and rear of the head, where the rocker arms are mounted to. it was actually only the rear ones, and put a new valve cover gasket on and have had no problems since with disappearing oil.

[DSchultz325e]

get an undercarriage wash?

[Kruzen]

mine does the same sometimes. It just takes a while for the oil to get to the section of the oilpan where the level sensor is. not a big problem. Mine was "eating" alot of oil too. I replaced the "doghouse gakets" on the front and rear of the head, where the rocker arms are mounted to. it was actually only the rear ones, and put a new valve cover gasket on and have had no problems since with disappearing oil.

As i have little knowledge of how an engine is put together, i'll look into this. thanks.

[Ryan Stewart]

I think on my M20 the oil passages were carbed up or something because occasionally a little oil would pool in the head. It would show low and then magically a half a quart would appear. It was strange.

[dwforum]

My engine oil light on the checkpanel won't always shut off. When I drive home from school I go up a fairly steep grade, and for some reason it always likes to turn on after driving it. Oil level is always fine, but adding more will never shut the light off. I usually end up driving around for a few days before it shuts off, as I know the level is okay.

[Kruzen]

Is the dipstick accurate after teh cars been running for awhile? or only when its off from cold start?