Replacement oil, Help!

[JScott]

Thanks for the help. Amazon is a little tricky here.  Some things ship easily like electronics but other items like food do not.  They also like to pile on a shipping charge if you're not watching.  I'm not sure about shipping lubricants from Amazon but there may be some 10W available here.  We're going into the "big" city tomorrow and I'll check the Home Depot/Lowes equivalent store.  There are also some specialty stores that may have it.
Any idea why they don't mention something like a plain old 10W-30 motor oil?  Is it the additives and/or detergents that might affect the seals?  

Some additional info; the temperature here never gets below 75 degrees F.  The high is usually between 90 and 95.  The machines are in the shade so probably operating at 85 to 90 ambient air temperature.