jasonp121 - I've got a 06 HSE. I've been trying to push the limit of the oil, I've been using German Castol AKA, GC \ CastrolSyntec Ow30\ Edge ow30. I pushed the limit to 9250 miles and got a TBN of 4.0 with very low wear metals. The TAN level (acidity) was 6. I think I could have reached 11K comfortably, but I've since backed down to 7500/8000 miles for the OC. I think you need to look at both the TAN and TBN to see how effective the oil will be on the longer interval.