Oil ratio for a Scott Atwater 16

[1946zephyr]

If it’s a full roller bearing engine, I would just run 24:1 in it. Non-roller bearing motors, I always run 16:1. Oil is the cheapest thing you’ll ever put in an outboard.

[Tubs]

A "Boathouse Repair" is one that done without having tools or the skills to do it properly.

• This reply was modified 6 years, 8 months ago by Tubs.
• This reply was modified 4 years, 4 months ago by Tubs.

[rudderless]

How did oil get so demonized…I just don’t get it. And I’m a climate guy…

[1946zephyr]

Oddly enough, I have never ran synthetic oil in anything: Ever. As long as the oil is changed at suggested intervals, things will be good. I may try it.

[rudderless]

Oiling requirements are different for 2strokes and 4strokes. Oil passes through once with a 2stroke. Oil recirculates many times on a 4stroke.

Think of oil as a plate of spaghetti. Nice long strands make good film strength. As the oil does its job the strands get sheared and cut up causing the film strength to go down. Synthetic oil resists this shearing better and holds its viscosity better with temp changes.

I use the synthetic oil at 10-30w in my autos from November until April. It starts easier at -10F and I wont be changing it during that period. Summer I use regular oil at 20-50w and change at 3000mi.

Sure, at 100,000 miles I assume with extended oil changes the synthetic would have an advantage. Change every 3000mi I am sure one would see equivalent wear.

Lube requirements for these older 2strokes are different than newer ones. One needs to use the mix no leaner than suggested in the original owners manual.

Thought this was covered already…

[jeff-register]

I believe politics play a part in the oil ratio mix. Better oils too have been developed as well. My personal opinion is to use good oil & mix per product data. That includes Mercury oils made for 2 stroke motors they built. As far as the fish we all know an internal combustion is not good for them no matter what oil is used. Bottom line!
I use brand name oils in the same & use Mercury premix in my Scotts. Never had a lubercation problem yet!

[Tubs]

A "Boathouse Repair" is one that done without having tools or the skills to do it properly.

• This reply was modified 6 years, 8 months ago by Tubs.
• This reply was modified 4 years, 4 months ago by Tubs.

[rudderless]

You do realize we are talking about the occasional use of an antique outboard motor…none of these examples are equivalent to the op’s original question.

I am glad to see I’m not the only one who’s been there, done that..congrats..

[Tubs]

A "Boathouse Repair" is one that done without having tools or the skills to do it properly.

• This reply was modified 6 years, 8 months ago by Tubs.
• This reply was modified 4 years, 4 months ago by Tubs.

[Pete]

While this probably will not address the original question posed here is a 1978 article by Gordan Jennings 2 cycle motorcycle expert. Although the article relates to air cooled 2 cycle race engines the discussion is valid for water cooled 2 cycle engines and how 2 cycle lubrication works on the innards. No flaming please as the environment was not addressed in this article which I agree is important, just oil ratios discussed. In my race outboards at sustained 7000+ rpm I use more oil as Gordan indicates in needed. In my service engines I use less (factory recommendation) since rpm operation is much different.

http://edj.net/2stroke/jennings/oilpremix.pdf

Mercury did extensive tests during their many hours of outboard running at Lake X Fla and the affect on water quality with the oils they were using. The results reported were no measurable change. Don’t know what oil ratio Merc used in their testing and I have never seen the report, would like to read it. I read somewhere that during their non stop 50,000 mile endurance testing they used much more premix oil than they recommended in their operators manual. I suppose they wanted to keep um running for the news. Yes today’s oils are better but the same lubrication principals still apply.

Everything eventually wears out even us.

[Author]

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