Reading the weight code of oil
5w30
5 is the "winter" cold range weight,
w is "winter" not weight,
30 is the warm oil range weight.
Run the weight that is specified from the manufacturer.
Modern engines have tighter tolerances than older vintage engines.
Using a heaver oil is not better.
Running a heavier oil can actually damage engines because it may not be able to properly lubricate into the tight areas.
I lways use what the manufacturer recommends. The 3.4 is 5w30.