I am a Mechanical Engineer in Fluids and Energy.
As far as 0W-40, that would be an excellent oil. You can always go lower on the first number.

 

I run exactly what the factory recommends, but I use Mobil1 5w20 and a Ford Racing oil filter.

I used to run my 7000 rpm 1970 Boss302 on 10w40 synthetic but then after reading an excellent oil thread on the Boss302 registry I switched to 10w30 in the car, it actually dropped my operating temperature by 10 degrees in 85 degree Florida weather on a very high strung engine.

That changed my mind about the thicker oils.