Originally Posted By: Redlinez
In reading the owner's manual and hearing inside talk from my Ford dealer friends (I was an advisor there too), the 5/50 is only really recommended due to track racing. Someone can feel to correct me if you think I'm wrong. Someone from Ford also said the internals are exactly the same as a non-track package engine. I only really started to think 5/50 is required due to the cam phasers, but after hearing a Ford rep say the engines are identical, I know now it's only for the extra protection while racing.
That was my understanding, I was told only the tune is slightly tweaked. You really need your sump temps to be sure what you actually need. Warranty is another consideration.
I'm no fan of 20w oil in a high performance engine but a nice 40w would be an excellent compromise and likely give you everything you need for the street.
Save that 50w for track days...