I have never even heard of this problem until the last week. My wife drives a 2008 Yukon XL 5.3 that we've had since new. The last oil change (Mobil 1 since new) I was 2 qts low, don't routinely check it cause never had an issue. I've lost almost 1 qt in just over 2k miles, 1st thousand I drove on interstate and didn't go down any, 2nd thousand wife drove around home, 55mph roads and thats when it dropped, that AFM thing would make sense then. 122k miles on it and wonder should I just keep an eye on it or is it worth doing this diablo tuner I'm reading about. I don't need any more power, just would like to drive it for a while. If turning off the AFM at this point would help I'm interested. I did replace the lost oil with Mobil 1 high mileage to see if that helped any. I did have it in dealer at 92k and told them about occasional ticking noise on startup, they said found nothing. Suggestions?