Though I think the weight difference is small -- isn't 90W gear oil about the same viscosity as 40W motor oil? Geo On Fri, Feb 13, 2009 at 3:39 PM, <DLylis at aol.com> wrote: > In a message dated 2/13/2009 5:11:20 P.M. Eastern Standard Time, > ...When I drained the 30W is ran far too thin for my liking so I went back > to 90W.