I have a Total Grip on my truck and am approaching 5k miles. With the M1 5w30 I was thinking I could extend to 6k (more perhaps?) I believe the oil could handle it, but I am leary of leaving the filter much longer. Come the 22nd this month time will be 7 months on oil & filter. Truck is no longer under warranty. Almost 41k miles and no probs so far.