Between me and my dad, we change alot of oil around home, we have five drivers in my family and both of my parents make their living driving, we currently have two cars, my explorer, to pickups with gas engines, two pickups with diesel engines, a dump truck with a gas engine, and a skid loader with a diesel engine
We change our own oil because
1) The closes oil change place is about 30 miles away and when you have that many vehicles to change oil in you would spend days driving them all back and forth
2) Oil change places usually charge a fortune to change the oil in a Diesel
3) We usually run 10w-40 in all the gas engines and 15w-40 in the diesels, most oil change places charge extra for anything over 5w-30
4) Generally we don't have much time to get this kind of stuff done during business hours
On my explorer I always use Tropartic 10w-40 which you can get at walmart for around $0.88 a quart, Fram PH8A filter from walmart for around $3-4 (Fram filters are nice becaust the end is coated with rubber so you can get a better grip on it), walmart generic STP oil treatment for $0.88, every 10,000 miles a quart of Slick 50 for around $15, everytime we go to walmart we pick up extra of everything so we have it on hand
Total cost: $8.40