OK, what is the deal with 5W20 weight oil? I really have always preferred at least 10W30. I got a new 2008 Jeep Liberty, 3.7 L engine, looks identical to the 2002 version as far as spec.

I recognize the 10W30 offer a little viscosity of oil, but isn't that a trade off for min. of oil related oil?

What happens if you go with 5W30 instead of 5W20? That 20 value with the high temperatures of modern engines seems to be asking for trouble.

Thanks