5w20 in the winter and heat of summer.

 

API rating chart http://www.aa1car.com/library/api_oilguide_2004.pdf
Ford Motorcraft oil 5W-20 http://www.motorcraft.com/products.do?item=15
Reduces friction
Minimize engine deposits and engine wear
Protects against high temperature oxidation and low temperature thickening, rust, corrosion and foaming

 

motor oil info http://www.bajajusa.com/oil%20not%20so%20slippery.htm
Here are some test data on different API rating oils from the Southwestern Institute. http://www.swri.edu/4org/d08/Abstracts/GasEng.pdf
API Engine Oil Classification API SJ http://www.infineum.com/information/api-passenger-sj-sl-2004.html
API Engine Oil Classification API Sl http://www.infineum.com/information/api-passenger-sj-sl-2004.html
API Engine Oil Classification API SM http://www.infineum.com/information/api-passenger-sm-2004.html
Oil Analysis http://theoildrop.server101.com/ubb/ultimatebb.php?ubb=forum;f=1
-BUCK-

 

Oil filter magnet, seems like a good product http://www.filtermag.com/carcraft.pdf
http://www.filtermag.com/tech.php