Like someone stated above, you have to remember that most commercially sold 2-cycle oils on the market (no matter who makes them) contains a lot of solvent, the Amsoil 100:1 does not contain these solvents. So at 100:1 your getting about the same oil protection as you would with a commercially sold oil at 50:1.
On my 44-year old Lawn Boy I have always used the Lawn Boy oil mixed at 32:1 as recommended, and as stated it is 44-years old and I mow with it every week.
My Stihl equipment uses the Stihl synthetic oil mixed at 50:1 as recommended by Stihl.
I've never used the Amsoil though I am tempted to try it.
On my 44-year old Lawn Boy I have always used the Lawn Boy oil mixed at 32:1 as recommended, and as stated it is 44-years old and I mow with it every week.
My Stihl equipment uses the Stihl synthetic oil mixed at 50:1 as recommended by Stihl.
I've never used the Amsoil though I am tempted to try it.