JackD,
Good advice except that engine manufacturer's have now got their priorities screwed up by an act called the Moss/Magnuson Act (CAFE averages) which is causing car manufacturer's to recommend oil viscosities based on helping them with their Corporate Average Fuel Economy numbers rather than long term reliability.

Nobody in their right mind would recommend 5W-20 viscosities for new ultra low emission engines. However, both Ford and Honda are doing it.

It appears that the Germans are still putting reliability ahead of CAFE averages.