Fuel/Oil ratio

[cattail3]

I am a brand new boat owner with a 1982 140 HP Evinrude motor on the boat. I have searched various discussions on this topic but did not find one that fits my setup. What would be the proper amount of oil to add to my gas? Being an older motor I want to be 100% sure I am putting enough in to lubricate the motor. Thanks for your help on this subject.

[try123]

50:1 strictly. 2.6oz oil per 1 gallon gas.