On a couple of other boards i use to frequent there was always constant questions about oil. Heres my 2cents.
All synthetics are great. All! Some are 100% synthetic and some use dino base stocks and that really doesn't matter unless you are a statistical whore. Regular dino oil is very good also but you need to change it religously at the specified milage based on your driving style and conditions.
All synthetics are not created equal but you or i will never see the differences in performance and longevity. The most important thing about oil is you changing it when you are supposed to. If you want to make your engine go for a long time do your maintainance!
But seriously, the new guy's right*. As long as you're using a decent synthetic, your engine is much better off. I would warn you against running synthetic blends for very long. Over time, the heat in an engine will break "natural" oil down into sludge. One of the main reasons synthetic can be run so much longer is because it doesn't sludge as easily.
Redline is good too. I'm only saying that you will spend more for the top tier name brands when an "inexpensive" synthetic will do just as well. It is only a few bucks more but still it's more. For street dring mobil1 is just as good as redline. Really it's personal opinion. I will use mobil1. No special reason i've just mostly used mobil1.
Like i said before, you really can't lose with any of the synthetics. Desratt...hopefully you have some miles on your 05' cause that's a little thick at running temps. I'm new to the duratec so i may be wrong.