Hi all.
I haven'tposted many questions to the forum in the past, but just found this very interesting presentation from Shell in the USA regarding the advantages and disadvantages of various oil grades and their effect on fuel economy and engine wear in both light cars and commercial trucks. A bit heavy going in places but very informative. I am sure you will find it interesting The paper, which is 29 pages long is in pdf format. go to:- http://www.iantaylor.org.uk/papers/IMechEFE2000.pdf