Oil viscosity - why the 20W-50 BS?

I run Pennszoil 10/40 in my vehicles and 30w in everything else.
I also let them warm up for 1 minute before I move anything.
I do this to everything with a motor at cold start up.
I then take it easy till operating temp is achieved, after
that I feel safe to work it.
I add zinc to the oils on older motors and lead substitue
to the fuel.
I add Stabil to all fuels starting in October.
I also treat with Slick 50 or the generic it all my aircolded engines
a couple times during there lifetime.

What ever you use, change it on a schedule, filters included.
There isn't anything you can fix in a motor or machine that is cheaper
than clean oil and a squirt of grease.