I just bought this truck and went to change the oil. When I got the oil filter off I instantly realized it is much smaller diameter and length than the filter that my truck was suppose to take. It appears to have an oil filter adaptor installed on it. Couple of questions: why would someone install on of these? Is there a benefit to having one? What filter number do I run with this adaptor? The filter that came off of it is a Wal-Mart Tire and Lube filter. When I google the filter number that came off the truck it appears to be a filter for a bunch of different V6 engines. I didn't see where it was used on a V8. I would think the filtering capacity is greatly reduced with this smaller filter. Should I leave the adaptor on or attempt to remove it? I have attached some photos. Thanks everyone for the help.