Two months ago my dealer replaced two injectors because of a skip on start up and oil level about 3/4" over full. Three thousand miles later my oil level is creeping back up but w/ no skip. I haven't had a oil analysis done but I assume it is diesel bringing the oil level up. What kind of tests can they do to diagnose this? I know warranty will take care of it now but I dread what will happen when the warranty is gone.