Fuel:Oil Ratios

[shane-r13]

Got a few questions about recommended fuel to oil ratios for various outboards.

1946-49 Johnson Td20 and Hd-25 – I’ve read original was 16:1 and some say now to run 24:1. Why not run original ratio?

1978 Artic Spirt 20Hp (same motor as Suzuki DT-20) – I don’t know what is the recommended. 40:1?

Thanks for any input.

Shane

[crosbyman]

the oil is better today…

Joining AOMCI has priviledges 🙂

[aquasonic]

Opinions will always vary on this topic. For T and H series motors, I stay with the recommended 16:1 mix using TCW-3 rated oil. Back in the day, 40W automotive oil was used, but it left a lot of deposits.

[jerry-ahrens]

Agreed, stay with 16/1 on the TD and HD motors. Both have a rotary valve built in to the crankcase that needs the extra lubrication. If you run them on 50/1, it will ruin them. I don’t know on the Spirit engine.

[Randy in Tampa]

i never killed a motor by using too much oil… 😉

[2fast4me]

I had a DT50 the manual said 40/1 TCW3, but if you used Suzuki oil the ratio could be 50/1.
I also had a 15HP Suzuki that was labeled on the motor 100/1. I always use recommended ratio except for the100/1.

2Fast4Me

[shane-r13]

ok, I agree with crosbyman that oils are probably better today, but i like the idea of the 16:1 extra oil. As long as the motors are not fouling plugs i cant see the harm in the extra oil. Might even help to fend off some the mosquitos on the back lakes haha. Now if i could just figure out this Artic Spirit 20Hp as it will be my main girl this summer.

[chris-p]

I believe the Arctic is a 50:1 ratio. I have the Suzuki counterpart that I run 40:1 on though. I always run on the side of caution with a little extra oil.

Oils are better today. That means you can run proper ratios without fouling plugs and having carbon build up!

The HD and TD NEED the 16:1 ratio to run properly. They run like crap on a leaner mix. The 16:1 mix helps lubricate, but also SEAL.

If a motor is smoking and dumping excess oils into the water they are not properly in tune or the oil is junk. I am a proud supporter of the XD series of oils by BRP. I run the XD 30 in all of my vintage motors at PROPER ratio. None of my motors excessively smoke or dump excess oil into the water.

[shane-r13]

I havent had any of these motors in the water yet, they have been winter projects. But i have an 1974 Evinrude 15HP and i find it smokes when going from trolling to high speed. I Run 40:1 in it and figured this was "normal". Maybe i’ll have to tune up that carb as well. I usually run synthetics, I’ve never bought a new motor so i don’t know why i run it, but i figure while i own the motor I’ll run decent oil through them. Thanks for the tid bit on the Arctic motor, i’ll give 40:1 a try.

[Mumbles]

quote Shane.R13:

1974 Evinrude 15HP smokes when going from trolling to high speed.

This is one sign of a motor getting low on compression or running too cold. The thermostat in these motors must be installed and working properly to keep them up to temperature. If the thermostat is good, a compression test and slightly hotter spark plugs may be required. This is after assuming the idle mixture isn’t set too rich.

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