I've always changed my oil every 3500 miles. I got a 2014 vehicle a few months ago and in the manual it says to do an oil change about every 7500 miles. I've driven it about 4k miles and the oil life monitor still says 66%. It's a little unnerving for me to let the car go that long. Has anyone had problems letting the car determine when it needs an oil change? The oil looks used but really dark yet.