Quick question on oil fuel mixture

[jonndena]

I have a 1961 Mercury 400 45 Hp. I am just wondering what the fuel/oil ratio is for this motor? I know some of these older motors ran a richer mix then newer ones. I just want to be sure. Thanks in advance.

 

[jake505]

Re: Quick question on oil fuel mixture

well according to my 1969 mercury repair manual you should use mercury formula 50-d or now i think it is quicksilver 2-cycle outboard oil or in the case that those are not available a tw-c 2-cycle oil should be used at a mixture of 25:1 for break in but since it is close to 50 years old i think we can assume it is broken in since it is broken in then it is a mix of 50:1