Muleskinner,
Lots of good info in that article, some out-of-date stuff, and a couple of errors.
The current ILSAC oil spec is GF-3, and that is in the process of being replaced withGF-4. The current API Service Category for gasoline engines is SL, and that will be replaced with SM around the end of this year. Each newer spec is better oil for better, cleaner engine protection and longer oil life.
"Energy Conserving II" is an obsolete designation.
I like his comment about over-the-counter oil additives reducing the friction in your wallet to allow the money to slip out.
The liquid, oil soluble, invisible moly used in motor oil is molybdenum dithiodialkylcarbamate; the phosphate version is used in some greases or gear oils. I haven't seen any tungsten antiwear or extreme pressure compounds, but have seen some antimony and boron compounds.
Generally, oil one viscosity grade heavier is no problem in most engines. Engines used in many parts of the world have many different oil viscosities specified for the same engine depending on local custom and regulations. In the U.S., the government pressures the car companies to get the best fuel mileage, so we see lots of 5W-30, sometimes 5W-20, specified. Our same 2UZ-FE V-8 engines have 20W-50 recommended for them on Valvoline's Australia's web site, 'cuz that's what folks down there think is the right stuff to use.
Oil viscosities are tested at 40°C (not 40°F), at 100°C, and for the "W" rating, at -25°C for 10W, -30°C for 5W, etc., according to SAE chart J300
http://www.infineum.com/information/viscosity.html There is no testing of oil viscosity at 0°F. So-called multiviscosity oils, 5W-30, etc., are not spec'd or tested at 40°F, they're tested at -30°C and 100°C for the 5W-30.
Ken