What is the best 5W-30 not just for wintertime, but for all year use? Of course, we probably should make this a three part question.
What is the best 5W-30 conventional?
What is the best 5W-30 blend?
What is the best 5W-30 synthetic?
I'd say either the Amsoil Series 3000, 5w-30, which I think is their best formulation right now, or the Redline 5w-30 which I'm very impressed with. Those are also going to be the most shear stable 5w-30's out there, simply because they use higher molecular weight basestocks than cheaper, PAO or group III based synthetics ....
The best 5w-30 you can get for $4.00 per quart would be Mobil 1. There are also some excellent Group III based, 5w-30's and 5w-40s available for $3.75 per quart in gallon jugs. The Petro Canada stuff is exceptional I think ....The Schaeffers S7000, 5w-30 is far and away the best synthetic blend I've seen - if you get it in bulk I think it's around $2.50/qt.
M1 Super Syn
Why? Because that is the oil I just put in my 03 4.7L V8 Ram last night. Yeah, no Hemi. I am also going to put this oil in my 01 Camry soon.
In all seriousness. Why? I honestly do not have a technical answer for you. I did a lot of reading on this site. When I start reading on this site my brain gets overloaded. My friends will tell you that it doesn't take much.
I read for a while and this particular oil is looking really good. I am telling myself "this is the oil". Then all of a sudden someone is saying it is crap. After a couple days and nights of reading about all of these oils with no real answer available about which is the best. I just picked one.
You have to start somewhere. And I decided to start with the M1 5W30 Super Syn. After all I have had the factory fill, the dealer bulk fill, and 1 personal fill of 5W30 Havoline. All of them were dino. I have never had a UOA done before, but at around 3K I will do one on this oil. I drive 75 miles a day 5 days a week, so I am looking for that extended drain interval.
This is the first synthetic oil I have ever used.