I change my own oil in my 2004 Maxima. The manual says to use 5w30 grade, but I've been using 10w30 and I change the filter every time. Had no problems with engine noise or operation.I add a bottle of Lucas fuel injector cleaner every 3000 to 3500 miles. You can stretch it to 3700 if you want. Just check your dip stick for proper levels every so often.