Not sure about mixing 100 to 1

[GeorgeJ]

I have my new Yamaha outboard calls for a 25 to 1 fuel to oil ratio for the first 10 hours. I'm good with this it sounds right but then they are talking about a 100 to 1 ratio, now I've been away from outboards for sometime and I know things have changed but that seems pretty lean. Are you guys sneeking in a little extra oil when your mixing for your out board or are you following the recommended mix? Hey and no smart answers from you 4 stroke guys!

[Sinker]

Nope,that's the right mix. 10ml of oil/L of gas.

 

Thats why I said there isn't much oil in your yammy 2 stroke.

 

Sinker

[ERB]

I work at a marina and all are customers boats that say to run 100:1 run 50:1 in them with no problem. 100:1 seems kinda low.

[Sinker]

I work at a marina and all are customers boats that say to run 100:1 run 50:1 in them with no problem. 100:1 seems kinda low.

 

 

Sure, they'll burn 50:1.......heck, they'll burn 20:1........but you don't need it.

 

Sinker

[boatman]

I work at a marina and all are customers boats that say to run 100:1 run 50:1 in them with no problem. 100:1 seems kinda low.

 

I personally think that's because 50:1 is so ingrained in us that people aren't comfortable with less. I know some old timers from back when outboards ran 8:1 to 24:1 ratios that won't use less than 36:1 in newer 50:1 machines.

 

Tolerances are much closer, bearings are smoother and fuel is used more efficiently in new outboards. The motor is designed to have fuel and oil lubricate the engine in very tight passages and spaces. Too much oil and it may be too thick to flow into some of these places, which will effectively under lubricate the engine. Old engines needed the extra oil to add as a buffer to make up the "slop" in the engine tolerances. Unless you know more than the engineers at Yamaha I'd stick with 100:1.

 

The initial 25:1 mix is required mostly for ring and cylinder break-in. Everything is very tight and full of machining marks when new. So the break-in period is the period where the internals seat together and smooth all the rough machine edges out. That means there is extra wear at first and requires extra oil. Once the engine is broken in the extra oil is no longer necessary and may actually be a nuisance. Also, make sure you use conventional oil for break-in. Synthetic is too effective at reducing engine wear.

 

With all that said, I run 50:1 in our 100:1 Yamahas at work only because the motors have limited seasonal use and may sit for extended periods in cold storage. These motors need to be ready to go at a moments notice so I don't fog them. As fogging sometimes creates problems at first start up after storage. 50:1 ensures the motor's have extra oil coating the internals in case they dont get used for a long period. If they were my personal motors I'd use 100:1.

[pike slayer]

awesome reply boatman, you really hit the nail on the head! i'll be msging you when i have outboard motor problems haha!!

[Bernie]

When I was a kid we mixed #30 oil with gasoline at around 24/1 ratio.

Then they came out with a 50/1 oil late 60's. It wasn't so much tolerances as it is the chemical makeup of the lubricants.

We have several engines we run 50/1 that were built in the 50's that work quite well.

Never really noticed much differences in tolerance on a crankshaft bearing overhaul from 1957 to a 1997 OMC.

They all used needle bearings on the crankshafts.

Part of the reason is emissions, not too many like the smoke. So they produced an oil that requires less to do the same job.

[Guest steel'n'esox]

How do you keep the mosquitos away with 100:1, I run 50:1 Amsoil, and mix it myself after my OMC blew up do to oil injection failure which is common with OMC, 60 and 70 HP engines, my old short shaft 73 9.9 is still running today, along with lots of older model green and maroon cover johnsons.

[cranks bait]

When I used my grandfathers Johnson 4 horse 20 years ago it used 100 to 1 ratio. Never had a problem with that motor. It even sat for about 5 years while I was out west (nobody used it but me) without being winterized or anything. Started up on the first pull clean as a whistle.

 

They put the ratios on the motor for you. Think of it this way. They are the people who do the research and development of this stuff. I think they know what they are doing.

[boatman]

When I was a kid we mixed #30 oil with gasoline at around 24/1 ratio.

Then they came out with a 50/1 oil late 60's. It wasn't so much tolerances as it is the chemical makeup of the lubricants.

We have several engines we run 50/1 that were built in the 50's that work quite well.

Never really noticed much differences in tolerance on a crankshaft bearing overhaul from 1957 to a 1997 OMC.

They all used needle bearings on the crankshafts.

Part of the reason is emissions, not too many like the smoke. So they produced an oil that requires less to do the same job.

 

Most OMC motors had roller and needle bearings by 1957 and could safely run on TC-W oil at 50:1. The 10 hp did too, but the wrist pins in the pistons were too small and got beat out. That was corrected in 1961. All smaller hp engines still had friction bearings that required more oil. By 1964 everything above 6 hp had fully jewelled bearings. OMC changed the recommendation to 50:1 in that year. The serviceable lifespan of the 3 hp was then significantly reduced.

 

There is also much debate on the subject. Many believe the thinner TC-W oils shouldn't be used in the old motors built before the 1960's with some exceptions, of course.

[Kerry]

I use Esso semi synthetic in my old 72 50 evinrude and mix it probably between 50 and 55 to 1,third year on the same plugs.On my 9.9 kicker I'll run it at 60 to 1 and could probably go higher as I don't run it full throttle.I also run premium gas only.

Kerry

[JohnAB]

Lean and rich refer to the air gas mixture in a motor and has nothing to do with the oil gas ratio. Some say that by running more oil than recommended you are actually leaning the motor out which is a definite no no as that will melt down your motor. Lean refers to too much air for the volume of gas being supplied which will cause your engine to run hot which will melt your pistons or burn a hole thru the top of your pistons. If Yamaha is recommending 100:1 that is what I would use. At idle and trolling speeds, most motors with oil injection are probably running around that 100:1 or even a bit higher ratio. When the motor is at full power it will tend to want more oil to help with the increased heats generated in the combustion process.

[Billy Bob]

I have a 1985 50 hp Johnson that is a VRO (variable ratio oiling) and it runs as lean as 150:1 when trolling and idling. After 24 years of a LOT of trolling on Erie and Ontario plus lots of high speed traveling it runs exactly the way it was when new. As a matter of fact I fished with a old fishing buddy I haven't fished with in about 10 years Friday and he started laughing when I started it up for the first time Friday morning. I asked what's so funny. He said "that motor still runs like it did when you purchased this boat, no knocks or anything. It just purrs". Well you know I never thought of it that way until he made that remark.

 

BTW for a LONG time I have been using Walmart's SuperTech 2 cycle oil in it. When I seen how well it ran on it (i think it's LuberMatic Oil) I purchased 5 one gallon containers at $7.77 each. Only got one left after filling up my 2 gallon reserve Thursday but I did price them about a month ago and if I remember correctly they are $8.95 now.

Edited March 29, 2009 by Billy Bob