I'm curious if the higher mileage guys are using synthetic or dino. NOT starting an oil debate, just wondering if there would appear to be a difference in engine longevity between the two different types of oil. I use Rotella for the most part. I have also ran Mobil's diesel oil. My commute quite often leaves me sitting in traffic, in summer, road surface temps easily top 130º. 2004 L, no oil cooler, Dave's mods, E2 can, Uni filter. 31k, uses about 1/2 quart of oil per 1000 miles.