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Fuel/oil ratio for Johnson 15 hp

T

T Ranger

New member
Good morning all. This is my first time on and I have a dumb question. Forgive me. I am new to forums but not to outboard motors. I have a 93 15 hp johnson and I would like to be sure of the fuel/oil ratio she would be the most happy with. I am thinking of using Amzoil interceptor 2/cycle oil any thoughts? Thanks.
 
Always mix at 50:1 using a -TCW-III oil.---------------Never mind what some containers say about being good for 100:1--------------When a manuafactures suddenly says their motors can run at 50:1 instead of 25:1 what are the REALLY telling you.---------------They are saying your motor will run nice with less smoke but not for as many hrs !!!!
 
One tip here: this really depends on the speed you will be running your motor. If you will often run at full throttle, use 50:1 and err on the side of too much oil. If you will be trolling or primarily only using the motor for getting out of a slip, you can get by with a higher ratio (less oil), but I wouldn't personally go above 70:1. If you have black gummy oily sludge coming out of the exhaust, chances are your ratio is too high. I typically run about 60:1, and I keep a small vial of the difference to add to my tank if I sense the need to motor some distance at full throttle somewhere, like back to the dock. When this happens, I usually have some sludge in the exhaust that will need to be wiped up afterwards.
 
Odd, when I do that, I get tons of unburnt oil out the exhaust. I even have to make the motor run a little leaner when I'm just running at low RPM for a long time, otherwise I get lots of smoke and have a nasty cleanup job at the end of the day.

I also just checked LeeRoy Wisner's fine article at http://www.leeroysramblings.com/Johnson 9.9_15.htm and he says:
Akin to the above situation, where spark plugs have continually become fouled, I have been experimenting with using 2 gas tanks for the last eight years now & for me I am happy with the idea. One, a 3 gal. tank, mixed at 100-1 with full synthetic oil & it is used ONLY FOR TROLLING, the other is the 12 gal. main 50-1 tank also used for my 70hp outboard jet on the same boat. Again, I am using the 100-1 synthetic only for trolling with the 9.9. If & when I need to run with this 9.9 motor faster, I simply switch to the larger 50-1 tank. However the winter of 2007/2008 in an emergency flooding situation, where I was rescuing a lady & her son who were stranded in her house & the water was still coming up fast, my main 70 hp jet water intake had become plugged with floating grass or hay, making it useless. It was getting dark & we were caught is a strong very swift current pushing me broadside to a fence, I did not have time to change the fuel tanks as I was broadside to the current & the 9.9 was then my only source of power then. I ran this motor at full throttle during the last half of this rescue mission for probably 20 minutes before I got to dry ground & offloaded the passengers. As of 2011, I am still using this motor with no apparent harm. But I was using the FULL SYNTHETIC oil mix.
Click to expand...

So now I'm not sure!
 
The purpose of oil is to lubricate the engine.-The burning of the oil is just an unfortunate happening in the engine.------It is the nature of a 2 stroke that some fuel and oil go thru the engine without being compressed in the cylinder.----That is what you see coming out the exhaust , especially an engine that has a faulty thermostat and is used for a lot of trolling.
 
Yes, but that wasn't the question. kimcrwbr1 claims that when trolling you want more oil in the fuel. However, what I've noticed is that if you run at low RPMs (like when trolling) then it seems like I get a lot more black stuff, and so I assumed you want less oil in your fuel so less of it just goes away.

I just not so sure now. Maybe I shouldn't reduce the oil when using low RPMs?
 
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