Oil??

Lots of threads about this subject. You'll find a ton of reading material if you do a search.
There is certainly nothing wrong with sticking with the 5w20 synth blend, but many of us have switched to full synthetics, myself included, with positive results.

Do a little searching here and on other car forums about the benefits of synthetics. Lots of good info out there that you can use to decide if the benefits are worth the extra expense.