Amzoil 5W20 Signature Series (100% synthetic). A client who manages a fleet and my brother turned me on to this product. I was a Mobil 1 user then went w/ Amzoil. The intervals are 25,000 miles or 1 year. I use this product now on all of my vehicles. I get their 25,000 mile filter, which provides excellent filtration. Truck runs great as does my other vehicles!