I've found two sites (maybe they are mentioned someplace else in this forum) that helped my understanding of synthetic oil for gas and diesel engines. http://www.vtr.org/maintain/lubricants-redline.html#recommendations
A vintage Triumph site and Redlines own site http://redlineoil.com/products.htm
look under engine oils. If anyone knows of similar sites for Mobil and other synthetic producers let us know!