Yes, another fuel oil mix question :(

[Fastwin18]

My Johnson AD-10 owners manual says to use a 1:16 mixture. Yet I came across this common parts list from 1964 which mentions 1:24.
I’m aware of the brass bushings and pros and cons of using these mixtures but I was wondering if anyone of you has actual experience with running these engines on a 1:24 mixture?

[fleetwin]

Well, it is up to you.  Personally, I disagree with this recommendation, especially on the 7.5hp models, which are more prone to rod failure.  I know, today’s oils are better, true enough.  But, they are not that much better.  The beauty of these engines is when they are in good tune, they hardly smoke at all, even at 16:1

Stick with the original 16:1 recommendation…

2 users thanked author for this post.

Wetfeet, Fastwin18

[Fastwin18]

Hi Fleetwin,

Thanks for your response. To be clear, I’m sticking to 16:1 as recommended, I’ve just finished a complete overhaul and paint job. Since this will not be my daily runner I’m not that concerned of using a 16:1 mix. It’s just that I’m curious if people have actually run these motors on 24:1 over a longer periods and how that turned out in terms of wear and tear. Is there actual experience that it’s bad for your engine at modest speeds, or is it just a matter of “better safe than sorry”?

[seakaye12]

As the years went by and consumer pressure mounted I am sure that there was “pressure from within” at all the outboard manufacturers to ease the oil mix requirements on their engines.

One only has to look at OMC’s decision to recommend 100:1 for a while;  before they started getting a bunch of warranty claims for blown powerheads.

I would (and do) stick to the original manufacturers recommendations on the 50’s engines .

1 user thanked author for this post.

Fastwin18

[The Boat House]

In 1971 the factory oil recommendations were updated again to 50 to 1.
To answer your question as to do people actual reduce the amount
of oil they run, I do. I run 3 oz per gal. (about 42 to 1) in most all my
motors and have been since the late 90’s.
Below are some I have on You Tube. The first one, 1928 Elto Speedster
is basically a parts built around 25 years ago to answer this question
for me. I don’t run it every year but when I do I’ll put between 45 to 55
gallons of fuel through it. All the motors posted on You Tube I have had
on a boat for a least a month except for the 1938 Mate. Most have made
it to the lake more than 1 summer. Most of my motors are pre. WW-II
bushing motors.
This is how I chose to find the answer to that question. I’m not trying
to tell anyone how much oil they should run. Just offering my experience.
Tubs.

1 user thanked author for this post.

Fastwin18

[Fastwin18]

. I’m not trying to tell anyone how much oil they should run. Just offering my experience. Tubs.

That was exactly what I was looking for, thanks.
And wow, 42:1 is quite a long way from the recommended 16:1!

[fleetwin]

Stick to the 16:1 in this engine…  Like I say, the rods on this style engine are “delicate” at best.  Make sure that lower crank seal assembly is correct as well, that is another good way of introducing water into the engine and throwing a rod.    There are surely some engines where a lighter oil mix is OK, but this isn’t one of them…

[Fastwin18]

fleetwin wrote:

Stick to the 16:1 in this engine…

Fleetwin, I’m not planning on using a different mix. As I said, just curious what people are actually using and how that turns out.
Tubs experience for example is most interesting and definitely food for thought. But I’ve put too much time and money in this motor to start experimenting with it.

I might with another one though..

[outbdnut2]

More oil is cheap insurance. I use Walmart house brand (Super-Tech) outboard oil that is TCW-3 rated. It’s usually not on the shelf with the name brand oils, but at the end of the aisle on the bottom shelf – I buy it in gallon jugs. I run my 24 to 1 and 16 to 1 motors at 20 to 1, because it’s convenient to dump a quart of oil into a 5 gallon can of gas and then top off the outboard tanks from that. I run my 50 to 1 motors at 40 to 1, putting a pint of oil into 5 gallons. When I run a motor on a homemade 8 foot hydroplane, since it is revving above max rated RPM, I double the oil.
Dave

2 users thanked author for this post.

olcah, Fastwin18

[jeff-register]

I’ve had many OMC & Mercury outboards & a dual deluxe 17 footer 2 stroke OMC 2 V-4 88hp motors. I ran 24 to one on the OMC boat per manual & all others on l5-1. I always used either OMC or Mercury brand oil except my 1954 15hp Evinrude super fastwin.  Inside the shroud it stated to run one quart of oil per 20 quarts of fuel. I used a G.I. can 5 gallons – one quart to 19 quarts mix. The manual said 1 quart to 16 quarts also. Never had any issues with that motor, ran very  well. I never opened it up because it was on a plowing hull not a plaining  hull, about 3/4 throttle max. Also I always mixed the oil with 2 gallons of fuel per quart, then added the rest of fuel to get a great mix, every little bit helped the motor plus I never had an open quart of oil on board to get contaminated with dirt or water.

[Author]

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