"dean" writes:

Because every professional user I have ever seen is using 10W30 engine
oil. Now I'm not about to put that into my Stihls but I was just
wondering if I am wasting money on expensive bar oil?

The oil on the chain will be distributed in you environment it's
totally unacceptable to use a non-biodegradable oil for lubricating
the saw. The pro's you have seen obviously don't care a dam about the
rest of the world and should be [insert punishment of choice]...

--
Dr. Juergen Hannappel http://lisa2.physik.uni-bonn.de/~hannappe
Phone: +49 228 73 2447 FAX ... 7869
Physikalisches Institut der Uni Bonn Nussallee 12, D-53115 Bonn, Germany
CERN: Phone: +412276 76461 Fax: ..77930 Bat. 892-R-A13 CH-1211 Geneve 23