Ever since I changed my oil (Mobil 1 5W30) I get a strong vibration/un-smooth engine when I floor it. This only happens when my RPMs are over 4000. Do not reallynotice this in 1st gerar but in 2nd I notice it everytime. Can't not comment on 3rd-5th gear (too fast). Anybody know what can be causing this problem. Could something have gone wrong with the oil change or is this a new problem. Thanks for your help