2HP Mariner/Yamaha

[puddle jumper]

I just got a 2HP Mariner and as close as i could tell its Yamaha made. The mount has been changed so i don't have the serial number. The mounts serial tels me its a 1992 Yamaha but that's not the engines original mount.

What im asking what is the oil mix. The old owner said it was 25/1.

Is there another place on this engine that i might find out the year so if i ever need part i can get the correct ones.

Thanks for any help.