B. But anywhere in there is just fine. (Including the fact that it will read slightly differently if it's just been running, then if it has sat for a while, like overnight).
I'll disagree. The three lines indicate the level - bottom line is low and top line is full.
It's perfectly OK to run it at L. You still have approximately six quarts at that level so nothing to worry about.
Might the owners manual show a photo of full on the dipstick? Another thought is upon the next oil change check to see level on the dipstick. Just make sure you are on level ground where you do this and at least let the engine run for a bit to fill the oil filter up. Then let it sit for a time for the oil to return to the oil pan.
just my 2¢
The owners manual shows a diagram of the dip stick but does not indicate where the true "full" level is. It just says something like fill to the F mark. I know the Atlas 4.2 is supposed to take 7 quarts but that seems to put it just above the "B" level and I didn't know if that was overfilling. The plastic end is always very difficult to read. I'll be grabbing a metal one the next time I'm at a parts yard.