I have a 2003 Infiniti G35,5speed Auto with 12,000 miles that sees a mix of highway and commute usually 10 miles each way. The weather in the San Francisco Bay area is moderate, and not too hot and not too cold. The owner's manual states that for severe driving, I should change oil every 3,750 miles and for all other types of driving change every 7,500 miles. My first oil change was at 7,200 miles(?break in oil) and my second at 12,000 miles. My dealer uses 5-30 Quaker State. Should I use synthetic and drain every 7,500 or dino and drain every 5,000? Am new to this forum and am really impressed with the knowledge you all have. Thanks in advance.
George