Fuel oil Mix question

[ryanjames170]

So i know there are 3 basic different set ups for bearings in outboards Babbot, Bronze bushing, and roller.

my question as a rule of thumb what are the fuel oil mixes one should run with these and what are exceptions to this rule? ie what motors would require more or perhaps less.

[chris-p]

Then there are the combinations of the above. Hard to answer as a general rule of thumb.

[fleetwin]

The best rule is to stick with the manufacturer’s original oiling specifications….Don’t be sucked into the bit about "today’s oils are so much better that you need less than originally recommended back in the day….". It amazes me how little smoke the old engines emit when running right, even with the heavy oil mix…

[amuller]

Agree with Chris–I don’t think there is a general answer to this question. Type of bearing isn’t the only factor.

I have Elgins and West Bends that are all roller but 16-1 is recommended. I run them at 24-1, same as my older OMCs that are partly plain bearing. They might run for years at 50-1, or they might not. The safest thing, of course, is to do as Fleetwin says.

OMC at one time said the little twins (3-4 hp) with all plain bearings could run at 50-1. Maybe; they likely had very low bearing pressures. But I would run them at 24-1. Forget running 100-1, and look with extra caution on motors from the 100-1 period.

Just my thoughts; this is an unending subject.

[ryanjames170]

Yeah I don’t Evan run my chainsaws or weed eater at 50:1 I run them at 32:1 and my mercs at 24:1 and Johnson depend on the engine..

What I was curious was more what bearing set ups demanded what oil mix… for a better understanding of what was going on as things evolved.

[chris-p]

Ryan,

You will get a WIDE array of responses on this one. We call it the great oil debate on here. Most guys don’t even bother adding to these threads as you are bound to somehow irritate someone. I would recommend as Fleetwin did, you cannot go wrong with manufacturers recommendations. When in doubt, extra oil wont hurt.

I run XD series of oils in my motors. Its a BRP product. I find it to be fantastic! Has cleaning agents, smokes very little, very little sheen on water. Its all I use now myself.

Some of the bushing motors, such as the 5hp TN/TD need the 16:1 mixture to actually seal as well as lubricate. They run better with the richer mixture. Just something to point out, as its not all about the lubrication factor.

[ryanjames170]

I had figured there was more to it then just lubercation.

I run mercury oil myself and yeah I’ve only hadone one engine smoke like hell and that was the Martin but it uses 12:1 fuel oil mix.. kinda a lot if you ask me. But perhaps there is more of a reason outside of bearings for it.

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