Ok, I have flip flopped several times.5w-20,5w-30 GC30, 5w-20 again. I bought the extended Ford ESP that will bring me out to 6 year 75,000, and have decided to be warranty compliant again, so my question to you is this: 5w-20 syn blend or 0w-20 M1. I will change at 3000 miles. Those are the only 2 warranty compliant choices I have I believe(at least that are readily available). I have the 4.6l Ford Supercrew 30,000 miles, with a Superchip tuner, and exhaust (also very mild piston slap when cold). I run it hard now and then and live in a climate that still hasn't dipped below 40 F (today it was in the 70's). I make mostly short daily trips to work (6 miles each way) and hit the highway for short runs a couple times a month. I know 3000 OCI isn't cost effective with the M1, And I am ok with the money issue, I just want the best protection for my engine for my driving conditions.