oil viscosity/quality 5w-20 vs 5w-30

Hello all,
Looking for some insight on any major differences and if i should have any concerns with oil difference.
So i've had my jkur for 3 months now (woohoo!)  . it has 73k miles on it and i just did my first oil change. i baught it from a non-jeep dealer and they offered a deal where as long as i do routine maintenance every 3-6-15k miles at there service center they offered a life time power train warranty ( i figured this was a good thing to go and spend the 30 to upto $300 depending on the scheduled service requirements) specially for a piece of mind with a warranty.
So i looked at the sticker they put on the windshield and it said 5w-30 (which is probably printed based on the manufacturers requirements) but then i looked at the print out they gave me and it said they used 5w-30. So i called back today and confirmed that they actually used 5-w30. I understand that 30 is a heavier weight but what would the pros and cons be?

its a DD and driven about 20 miles a day with the occasional longer drives on the weekends, wheelin and in the summer towing about 1600 trailer (with jetski).

Use what ever the tag under the hood says to use or look in the owners manual.
You stated that they used 5-30,is that the viscosity oil that the manufacturer says to use?
5-20 is a lighter weight and will flow easier when outside temp is low, resulting in less engine wear at start up in cold conditions.
On the other hand, 5-30 will remain thicker when engine is hot.
Alot of the manufacturers use the 5-20 for fuel mileage and also because the tolerences are closer on the newer engines so they in turn can use lighter weight oil.

If I recall correctly, 5w20 would only be less viscous than 5w30 when it's up to engine temp.

The first number is the cooled-off viscosity and the second number is the viscosity once the viscosity increasing additives (VIA) have been heated up enough to take effect.

(They're also one of the main reasons to change the oil, because their effectiveness fades with time and abuse, leaving your oil thinner at temp and less able to protect your engine)

Yeah that's what I meant to say!! Thank's Geoff.