I have checked my C63 engine oil as per the manual (10 minutes off after being at operating temperature). Everything is fine. Oil at max level.

If I check the next morning after it has been sitting all night, the engine oil level at the dipstick shows very low (add 2 quarts), right at the low cutoff.

Which is right? I don't want to overfill. Is it possible that when at temperature Mobil1 0w-40 expands that much?

 

If it is low, the car should send you a message saying something along the lines of "Check oil next time you put gas in car." Can't remember what it said exactly when I needed to add some.

 

So I guess the flipside to that is... how do I know the car isn't overfilled ... if it shows overfilled via the dipstick at operating temp, but shows max fill after it has sat overnight?

 

Not sure. I've only had experience with the low level. Hopefully someone with more knowledge will chime in soon for ya. Good luck.

 

I always check mine in the morning after sitting overnight. Mine is at the bottom of the top red tab as I just did an oil change. Maybe I will check mine after it has reached operating temperature to see what it reads.

 

There's also a message for overfill, so don't panic.

The oil is a lot thicker in the morning and will take a lot longer to coat the dipstick. Make sure you leave it in the tube for at least 10 seconds after cleaning it. You might be getting a false low on the cold oil.

 

The car is difficult to get consistent readings from

Usually takes a few tries to get repeatable results

Mine reads the same when hot or cold
My manual says to check 5 minutes after shutdown

Reads the same in the morning when cold
More oil drains raising level
But cool oil has decreased density ~10%
Level constant

Leave the dipstick in 5 seconds
I leave it in longer and give it a wiggle when fully seated
This seems to help repeatability

 

This. I actually leave the dipstick in for 30 secs. A quick in-and-out just doesn't seem to result in an accurate and repeatable reading on this engine.