Has anyone who has ever ran a 5.7l GM van had a problem with oil readings on dipstick? It seems the only time I can get an accurate reading is after it has sat overnight. If I try to check it during a fuel stop it always reads low. There is a mfg sticker right next to the oil fill that states max capacity for 5.7l engine is 6 quarts but I constantly have issues when taking it in for oil change the techs overfill it because at 6 q "it only shows half-full", then I make them pump it back out to max 6 q. After it sits it shows normal. I often wonder if I have the right dipstick. Then I think others must have had same issue as this is the first vehicle I have ever owned that has the sticker right next to the oil fill telling you not to overfill it. Any guidance here?