# fuel/oil mix on my older outboards



## newyota (May 8, 2017)

I see where some guys will run a 40:1 or something around that on the older 2 strokes instead of 50:1.The 1980's motors I have had the 100:1 sticker on them and if that is how they were run by the original owners I could see it causing extra wear.I assume as an engine gets some wear it may be helpful to prolong it's life?Anyone here do this?


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## CMOS (May 8, 2017)

I do. I have a 1966 Johnson 9.5 that runs like a champ. I opt to run 40:1 in her just to keep her happy for a long time.


CMOS


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## Sinkingfast (May 8, 2017)

Many years ago I read the change from 100-1 to 50-1 was about off time corrosion..not about wear. 

Not to start anything but..I run 20-1 in everything I own including my 4 stroke stuff. Keep in mind my daddy had to hide the oil can cause I'd oil everything..I mean everything.

I was brought up a long time ago when everything needed 16-1 sae40wt also.. so..


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## Stumpalump (May 8, 2017)

100:1 was a mistake to help with emissions. It should never be used on anything. 100:1 synthetic oil is available but it's for injected engines. That oil does not mix well or stay suspended so don't use it. 25:1 is best for WOT but it loads up so back it down to what your comfortable with. I run 40:1 Penzoil from Walmart. Luv that stuff. My new to me engine ran a little smoky at 40:1 so I'll back it down to 45:1. I measure carfull. No guessing.


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## Pappy (May 8, 2017)

I see from your other post you are referring to a 1985 model year. 
The 100:1 sticker on the engine pan should have been removed from that engine and the engine should have been run on a 50:1 mixture. 
A previous post indicated corrosion during off season and that post is correct. 
I also run additional oil in every two stroke I own and that is over 60 engines counting my antique and vintage fleet. 
One thing you will never hear of is a 2-stroke that failed by running a bit too much oil...... think about it :beer:


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## LDUBS (May 9, 2017)

Sinkingfast said:


> Not to start anything but..I run 20-1 in everything I own *including my 4 stroke stuff*.



I learn a lot reading the "Motors" posts. This just isn't computing. Am I understanding that you put a 20:1 oil/gas mix in your 4 stroke motors? Why would you do that?


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## ppine (Jul 4, 2017)

I have a 1929 Johnson 1 1/2 hp motor that is a family heirloom. It has a manual spark advance and a very primitive carburetor. I use old school oil ratios in it like 16:1. It makes a mess on the water though and I rarely run it. Anyone know where to buy spark plugs for ancient motors?


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## Pappy (Jul 4, 2017)

ppine said:


> I have a 1929 Johnson 1 1/2 hp motor that is a family heirloom. It has a manual spark advance and a very primitive carburetor. I use old school oil ratios in it like 16:1. It makes a mess on the water though and I rarely run it. Anyone know where to buy spark plugs for ancient motors?


PLugs are still available. 
Go to https://www.aomci.org and ask your question in there. Should have several answers in a few minutes! 
I also have a fleet of engines that run 16:1 all the way up to an opposed 60 cu. in. 50hp. If adjusted properly they do not leave much on the water.


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## ppine (Jul 5, 2017)

thanks Pappy. 
The carb needs some help. That is where the leakage seems to come from.


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## turbotodd (Jul 5, 2017)

Several of a million or so reasons why the EPA hates 2 strokes. Too easy to dump a quart of oil into a jug of gas that might only be a gallon. 

Perhaps no one has ever encountered a powerhead failure due to carbon'd rings? I have, unfortunately, a couple of times. Looks similar to a lean issue, burned piston. The piston rings dissipate combustion heat away from the piston and into the cylinder which is obviously water cooled from the outside. Once the rings begin to get carbon'd up, they can't dissipate the heat. Normally they just stick and you'll encounter loss of compression and/or low power due to contamination of the crankcase. Every once in a while I'll see one come through with a burned up powerhead, tear it down and find what looks sort of like a lean fuel mixture failure, but mostly seen on the sides of the pistons rather than the top. By that time the rings are usually stuck in the ring land. Get them freed/broken out of the land and behind it find a ton of carbon. I've only seen it twice in nearly 30 years, but it does happen. That's one reason oil injection is popular. Unless it's a VRO, which should have been scrapped many years ago.

They ran fine on 100:1, at least Yamaha's did. At one point all yamaha outboards up to 40hp were 100:1. I never had a single powerhead failure through the shop due to lack of lubricating oil (as long as it was mixed) but we did see some guys that didn't want to play by the rules and mixed them at 50:1 or in some cases 25:1, and those ones were the guys who complained that the lower unit leaked black oil out of it. Had one that was so mad that he called the factory, who sent out a RSR, inspected and came to same conclusion: over-oiled. Advised customer and he ran off with his tail between his legs but still loud about it. Sometimes I believe that you can't teach old dogs new tricks. Seen others where they forgot to mix the oil in and burned the powerhead, a 225 recently was a victim of that. Guy couldn't afford to fix it, was around $4000 estimated cost. Sad. Such an easy mistake to make on the old premix 2 stroke motors. The oil injected motors would remind you if the tank got low; but there is no such warning on a premix motor that I am aware of. On some of the PWC's (waverunners) the oil injector would inject the equivalent of about 120:1 at full throttle and the equivalent of around 300:1 at idle speed-and actually carried a warranty on them. I did see some of those burned up, but we were able to pinpoint the failure to a rolled over ski, which let the oil line and pump get air in it. The pump works great but they are not a very good air pump; it gets a bubble in it and it will stop pumping oil, period. The way we knew they were rolled or run completely out of oil was that there was a bleed screw in the pump; remove the screw while at the shop and let the oil run out. If there were any bubbles, it was run dry at some point. But I never once saw a ski or outboard pump failure, always had air in them and the owners blamed the pumps.

I'm doing an experiment at work with a jar of 50:1 premix fuel left vented to the atmosphere. Results at a later date as this is requiring some analysis from an independent/outside company. But it will let me know if my hypothesis is correct in that the fuel/oil mixture changes with the age.


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