With out a doubt, oils have really improved and the manufacturing tolerances are so much better, then just 10 years ago.
The lighter weight oil will give you better mpg especially in cold temperatures, but look at the owners manual. There should be an operating temperature range and a recommended oil for that range. Also, the 5w-20 oil may not be suitable for extreme duty defined as constant high speed driving or towing, but the manual should cover this as well.
If you're really worried about it, use a synthetic oil; and as others have pointed out, if the manufacturer recommends it, it should be the correct thing to use.