1 problem with over filling your oil, is that there is the chance of blowing out your seals. But if you only use 1/2 qt more it wouldn't be that big of a problem. but if you run 1 qt over like some there is a high risk of blowing out your seals.
On another note I just changed my oil and went with 5w30 Mobil 1 Syn, I put 5 qts in, 1/2 qt over recomendation (sp?) but after the pressure check it was only 1/8 qt over full? I guess the Purolator oil filter is a little bigger than the Fram I had last time.
