Reply To: Oil type

[Mumbles]

There’s a reason some older motors called for heavier oiling than others so I wouldn’t stray too far from the original specs. Experimenting could be dangerous and trying to save a few cents on oil could be costly in the end.

I’m not sure about the older Fastwins but the Johnson KA motors have a large rotary valve on the crank and need an 8:1 mix as do the Evinrude Big Fours which also have a large brass bushing on the lower end of the crank. For high speed and racing, 4:1 was sometimes the magic mix ratio.

Heavy oiling has payed off for these motors as they are still around and running 80-90 years after they were built. I’d like to see where a modern motor will be after that many years after running on 50:1 and lighter ratios.