Well I don't know if it is the oil level or the sensor. In my 2000 W220 S430 with 123,000 miles I have just started getting a low oil warning.

It occurs only after about an hour of highway driving. Stop with car off for over an hour and then on restart it warns me to go to workshop due to low oil.

If I do the electronic oil check (turning the key without starting and watching the display on the dash) at that time it will tell me it is a quart and 1/2 low.

However the dipstick tells me the oil level is in the middle of high/low range.

When I am bck to local driving no more warning of low oil level. However if I take another road trip I go back to the warnings.

Mobil 1 synthetic 0w-40 is the fill. I have owned the car for the last 115,000 miles but this just started 6 months ago. Regular oil changes between 5K and 10K miles.

Any ideas?