What oil do you use?
 

Changed the oil this past weekend using German Castrol 0-30W. AutoZone had a deal on it, and the oil nerds at http://www.bobistheoilguy.com/ seem to have a hard on for it. Car seems quieter at idle, and seems smoother running in the summer heat.

What does everyone else use?

Royal Purple 10w-30. Redline MTL for the transmission and Redline dif fluid.

I'm thinking about switching the transmission oil to Motorcraft though.

Castrol GTX 5w-30

I use the exact same stuff :O

Rotella T6 5w-40 synthetic. I run this in everything, miata, echo, xterra, and next oil change the avalon

Another Rotella T6 5w40 convert. For performance, price, and availability, it's hard to beat.

Amsoil in the transmission and differential.

Rotella T6 here too, used it in my NA as well.

Redline in the trans and diff.

I also use GC on the regular. I recently bought some 15w50 Redline to use during the summer especially for the track where its 100F ambient and my oil is like ------ water.

GC is great though, its pretty much a 0w40, so its a bit thicker than your average 0w30.

Rotella T6 Synthetic 50%
Rotella T6 30wt 50%

I run Rotella T as well since I get it buy the case for the Roll Back it's really cheap and a great oil.