I use ~4.5 qt and check the dipstick. I add the other half quart around 4k miles and change between 6.5-7k miles depending on the oil analysis that I do every at 6.5k miles. I basically change oil twice a year, use full syntheic and puralator pure one filters. I've had several oil analysis done at Blackstone that support my schedule, it is what is right for me, I don't know what it right for anyone else nor do I suggest anyone follow what I do. Driving habits, enviroment, oil and filter type and so on all play a part.