The Automakers are fighting hard to get better oils to satisfy lubrication needs of today's engines.
Notice how sludge is listed among other things. Motor oil technology always lags engine technology!!
http://www.imakenews.com/lng/e...fm?x=b4bMGRl,bhb871W
http://narbreview.blogspot.com...n-sludge-claims.html
http://www.imakenews.com/lng/e...346479.cfm?x=b11,0,w