Redline's great, kind of pricy and hard to come by when you need to add that qt when you least expected it. for a few dollars cheaper you can get some Royal Purple, i use 10w 30, i live in florida, i could probabley even use something thicker cause the year round heat, but i've been very happy with it, sometimes at oil chages i even subsitute a qt of royal purple with a qt of lucas Synthic oil stabilizer, it's also great stuff.
I use Castrol synthetic 5W40 but will probably switch to 0W40.All the oils listed above will do fine for daily drivers.Just remember the oil filter is just as important as the oil you use.Doesn't do any good to run Redline or Royal Purple if you are going to use the crapy Fram filters or the likes.Most synthetics are also made to run well above 10K miles.So if you are using a crappy filter that is only made to handle around 3K and you are doing OCI's at 5-7K then that could be a problem as well.
Redline or Royal Purple. They are both compatable with all types of oil, so if you need an extra qt of oil and you can't find any RP or RL anyting wil do. I use Red Line 5w30 and an OEM filter and I do 7000mi oil changes.
I use reg valvoline 5-30, trust that shit with my life, dad put 300k on a legacy before he sold it, never touched the engine changed oil with valvoline and that was it, far as i know the guy he sold it to is still driving it. I dont see what's so special about redline, if its so good why isnt it sold everywhere? Just playin the devils advocate.
Just to give you guys a heads up that are using Mobil 1, Mobil has reformulated their synthetic to contain "Group III" base mineral oils so that it wasn't really a "true" synthetic. Its basically dino oil now! I would recommend Amsoil, Redline or Royal Purple over Mobil 1 anyday. Something to think about, plus the stress and heat our motors take we need all the protection we can get. Just my 2 cents.