It is possible to raise your MPG just a little using synthetic. I wouldn't buy anything more expensive then the supertech synthetics sold at Walmart for a Toyota Camery. With 5 quart jugs and Super Tech oil filter, it cost about $15 a DIY oil change. Maybe a tad more with tax. If you only drive 15,000 miles a year, then that's only around $45. Not too bad for ownership upkeep cost.
We have a 05 Corolla 5sp rated at 41MPG HWY and I use the Super Tech syn stuff in it. We hit 43MPG once and we got stuck in rush our traffic leaving Chicago, so part of that tank was in stop and go traffic for about 45min. The rest was almost all HWY. Other Corolla owners have reported as much as 45MPG on newer Corolla's when running synthetic oil.
Whatever oil you choose to go with, change at 5K miles to keep your powertrain warranty.
Synthetic oil might not be needed, but I want to see how many miles this engine is truly good for
I used to use the regular supertech in a older car and it ran just as smooth as any other oil I have used.
You don't really need to get in to the expensive stuff unless you have a high performance car, drive like you have a high performance car all day long, or deal with extreme climents.
In some cars like Porsche, the newer Vetts, and I think even the Mitsu EVO have Mobil 1 labled on the oil cap. I don't know if you would acually void your warranty ( I havn't read the warranty book for any of the listed car), but Mobil 1 is the recomended oil for many sports cars now days. Some of BMW high end sports cars too.
All the Toyota dealers I've seen use Valvoline oil.
btw, if you want to give Super Tech syn a try and can't find 5-30, email wal-mart (find the contact link off of walmart.com) and request that the oil be sent to your local wal-mart. If you try and call your local wal-mart, you will wast every minuet of your life from the time you pick up the phone untill the time you hang up the phone. Nothing good will happen in the time used to call a wal-mart store. You will just want that part of your life back.