Ok. I know Nissan list the Xterra as taking 3and 1/8 quarts w/o the filter and 3 and 3/4 quart with the filter. Here's my question. Dont all dipsticks have a 1 quart variance? Meaning, if your truck falls below the hatched marks on the dipstick, you can add a full quart and you shouldnt be TOO full. Not that you can read the dipstick in the xterra, but where does the bottom hash begin (volume wise) and the top hash end?

The reason I ask is b/c I was at a nissan dealer today and brought 4 quarts of Mobil 1. I asked for half a quart back after the oil change. He said he put it all in, and if needed the X could take a little over 4 quarts. I wanted to call bulshit, but then thought about the leeway on the dipstick? Anyone know for the answer? What problems could arise from filling too full?
Thanks in advance for the responses.
John