it does not do anything particularly well. a mechanic friend of mine swears that many of the engine failures he sees are a result of this oil's inability to do the job. routine oil changes and engines just junked up with sludge. 10w40 was created by the oil companies to bridge the gap between oils for different climate conditions, hence the "super multi-grade" distinction. stations wouldn't need to stock many different grades so it was attractive from a cost standpoint. in my opinion it's kind of like "the jack of all trades, master of none" of the lubricant world.