In warranty I follow the manufactures recommendation on viscosity and API/ACEA ratings with an OEM oil filter. Once our vehicles are out of warranty I switch them all over to M1 0w-40 Euro with FRAM Ultra Synthetic oil filters. I figure it's a good quality oil that covers the bases across all viscosity ranges and is reasonablly priced when on sale. Most vechicles I run 7,500 mile OCI. It just makes my life so much easier with having six cars/trucks in the family.