We just changed the oil in our BMW 745li and it keeps on saying that the oil pressure is low. How do we turn it off? Or what might be the problem?

When you say the "oil light," do you mean the light that says "Change oil" or are you seeing the red light that indicates low oil pressure?

If you're seeing that red light, that likely means you have low oil pressure and should stop driving immediately, until the problem is diagnosed and repaired.

It's also possible to see the oil pressure light on when there's no issue with oil pressure, if the oil pressure sender has failed or there's a connection problem.

If the oil light you're referring to is the "change oil" light, you will need to manually reset it for it to disappear. Here's how (from Chrysler):

1. Turn the ignition switch to the ON/RUN position (do not start the engine).
2. Fully depress the accelerator pedal, slowly, three times within 10 seconds.
3. Turn the ignition switch to the OFF/LOCK position.
NOTE: If the indicator message illuminates when you start the engine, the oil change indicator system did not reset. If necessary, repeat these steps.

www.realoem.com

Yes, if the engine don't have enough oil to keep it lubed it will cause heat and friction that could damage or destro

check ground

Sorry to say but if you have to put in a quart of oil a day then you have a major problem. Sounds like you have ruined the engine. It could be seizing up.

blue or blue/gray smoke is a sign that engine is burning engine oil. keep an eye on oil level and if engine is getting hot or over-heated this will not help your situation.

Click on the following: direct FREE Links. They are the Serpentine Belt Pattern for You 2002 745li with the 4.4L DOHC V8 depending on your Engine Options.

Let me know if this helped....Thanks for using FixYa.com!
http://www.2carpros.com/car_repair_information/year/2002/make/bmw/model/745li/2002_bmw_745li_drive_belt_routing_diagram.htm

AND:

http://www.canadiandriver.com/articles/jk/images/bmw4pt4v8.jpg

Your BMW car has a variable time service according to the CBS daten control - Condition Base Systems control and car controled this data and must say what to need in the i-drive board computer/service control. an 100% I say to you as a change to spark plugs is it 100 000km is time of life spark plugs in car and fuel filter

If it just came on that there is low fuel pressure the first thing you should check is if there is a fuel filter(some vehicles don't have a changeable filter) and change it because they can plug up and restrict fuel flow over time. If the low fuel warning doesn't go out get your fuel pressure checked. Usually about 1/2hr charge in most shops.

The engine is low on oil. but assuming it is not.
The engine is either idling to low .
The engine oil pressure itself is low. The engine oil pressure switch is leaking or not reading the oil pressure in the car.
I assume there is not knocking noise from the engine.
I would check for any oil leaks on the engine .
IF there are no leaks , I would change the oil pressure sesnor or switch first .
This could lead into major engine work.

Good luck