I once owned a Homelite Super XL12 saw. I recall it being a 16:1 mix.
Now, I have 6 different saws and blowers and trimmers that are all Stihl. I use the Ultra Synthetic oil at 50:1 for all those machines. One gas can, one fuel. The oil bottles are for 2.5 gallons of gas to be added. I usually put 2.4 just to give a tadge more oiliness. No way would I run that mix in that old Homelite.
I believe that when the machine builder says to go 20:1, or 30:1 or whatever, they usually are referring to Major Oil brands, or names of product other than their own. I used Union 76 brand oil for years, in my Stihls too, but always followed the specific recommendation, I think it 25:1 with major brand stuff, never 50:1 with an oil like that. Stihl say 50":1 with "their" oil, I think that's safe with theirs, but probably not with some generic Wal-Mart cheapo brand.