100/1 or 50/1 oil mix

[Buxton Bob]

What is your opinion about using a mix of 50/1 in a 3HP 2001 Yamaha 2 stroke, that has been produced to use a 100/1 mix.
The motor in question has been running on 100/1 with no problems but is used a lot at full speed while pushing a 12 foot punt. With an extended tiller arm and one up in the boat, it gets along really well.
I didn't think of changing the mix until a mate said that he ran his on 50/1 as recommended to him by a mechanic.

 

[Bob_VT]

Re: 100/1 or 50/1 oil mix

Welcome to iboats.

It is really dealers choice when it come to the yamaha....... yes they were designed for 100:1 and 50:1 will work fine except you might have to change a spark plug sooner.

If it was my motor I am more of a fan of 50:1

 

[Buxton Bob]

Re: 100/1 or 50/1 oil mix

The more i think about it, the more i like the idea of the 50/1 mix.
I have two other motors that run 50/1 so one lot of mix does the three.
I'll be on the water within the next couple of days and i'll change the mix and see how it goes.
I really like this little motor and if more oil will make it last longer than that is a good thing.

 

[robert graham]

Re: 100/1 or 50/1 oil mix

The 50:1 will work fine and possibly give you some additional protection from internal engine corrosion. When you really think about it, the 50:1 mix(2.5 ounces of oil per gallon on gas) isn't a whole lot of oil. Do you also use Ringfree, Seafoam or Stabil in your tanks?

 

[SeaNymph Man]

Re: 100/1 or 50/1 oil mix

I would go the 50:1 route,...it's ALOT cheaper to replace a spark plug than it is to replace a piston and rings!

 

[F_R]

Re: 100/1 or 50/1 oil mix

I've never been inside a 100:1 Yamaha, but I'll bet Yamaha has engineers that are smart enough to design a motor that will withstand the ratio they recommend----or they wouldn't recommend it. I'll bet that thing has some sort of high tech cylinder liner or piston materials. Who are we to second guess them and say it is going to wear out prematurely?

Having spouted that off, I'd say it probably wouldn't hurt to use more oil. There are a couple of valid reasons for doing it.

Convenience (other motors running 50:1)
"Feel good" about it.

Cost of that little bit of oil certainly isn't a factor.

 

[M9.9]

Re: 100/1 or 50/1 oil mix

Hi OP and all,
I'd go with what the manufacturer says you should use and if it's 100/1 then use it. I can't be sure that an OEM such as Yamaha have not engineered lube-line tolerances where a thicker mix (dbl) won't interfere with deep lubricating such as pin rollers and deep seated bearings? Maybe a thicker mix will also interfere with free-flow in colder conditions on a Yamaha. Dunno, but why chance it?

 

[Home Cookin']

Re: 100/1 or 50/1 oil mix

75:1. Problem solved. Next?

 

[Eazzy]

Re: 100/1 or 50/1 oil mix

I like 72 7\8: 1.1

 

[steelespike]

Re: 100/1 or 50/1 oil mix

50:1 gives a little room if you somehow make a mistake mixing fuel.
It happens,don't ask. Also if for some reason the motor ends up in extended storage
there is more protection.

 

[JimS123]

Re: 100/1 or 50/1 oil mix

I also "heard" that 100:1 was bad, so I started to use 50:1. It smoked too much, so I went to 75:1 with no improvement. I asked my dealer (a Yami dealer for 25 years) and he yelled at me for not following the directions. He said he never had a yami fail at 100:1.

I then went to 100:1 and have been since 2007 and all is good so far. Can't understand it....all my evinrudes run fine on 50:1. Yamis must be smokers!

 

[dingbat]

Re: 100/1 or 50/1 oil mix

If you have every worked on 2 stroke that was run rich for any length of time you would stick to 100:1 ratio recommended by the manufacturer

 

[Buxton Bob]

Re: 100/1 or 50/1 oil mix

Thanks for all the opinions, I have decided to stick with 100/1 for now. My mate running on 50/1 does say that his engine smokes a fair bit and is also going back to 100/1
Happy motoring, Bob

 

[Pascastel]

Re: 100/1 or 50/1 oil mix

I would personnaly go with the 75:1
A bit more oil than 100:1 for additional protection, but not twice what's recommended.

 

[JB]

Re: 100/1 or 50/1 oil mix

The downside of a 100:1 mix only showed up on OMC outboards and only in extended storage; a few crank and associated parts picked up surface rust.

That could well be traced to the alloy used in the crankshaft related parts, but OMC chose to change back to the 50:1 recommendation rather than recall a bazillion outboards. A bit more nickel or chromium in the key parts might have avoided the rust problem.

I have heard of no complaints or failures of Yamaha outboards traceable to using the recommended 100:1 mix. I do not know why the same problem in storage has not appeared, but I could speculate that the Yamaha parts are of a different alloy or are treated differently in manufacture.

That said, I would probably run 50:1 full synthetic in a Yammy, if I had one. Yeah, I guess that is the definition of conservative.

 

[Frank Acampora]

Re: 100/1 or 50/1 oil mix

Addressing the "thicker mixture" -- Internally there is no difference: When the fuel is vaporized in the carb, the oil, because of its much lower volatility, is not vaporized but assumes a small droplet or mist form. So, at any ratio you have two different phases--Vaporized gasoline and droplet oil. Ratio of oil will not determine how "deep lubrication" is acheived. As long as there is sufficient oil for the engine design, all internal parts will be adequately lubricated.

 

[rubenmromero]

Re: 100/1 or 50/1 oil mix

Thank you Frank,very well stated.

 

[Lone Duck]

Re: 100/1 or 50/1 oil mix

Addressing the "thicker mixture" -- Internally there is no difference: When the fuel is vaporized in the carb, the oil, because of its much lower volatility, is not vaporized but assumes a small droplet or mist form. So, at any ratio you have two different phases--Vaporized gasoline and droplet oil. Ratio of oil will not determine how "deep lubrication" is acheived. As long as there is sufficient oil for the engine design, all internal parts will be adequately lubricated.

This is true. But!! The engine is designed to burn off 100 parts of fuel to 1 part oil during combustion.keeping the cyl and rings clean.
If you use 50 parts of fuel to 1 part oil , some of the oil will not completely burn off causing more oil in cyl and muffler and a very black spk plug. Also after shut down the unburnt oil will seep down ex and intake ports and collect in the crank case. So on the next start up you get a larger load of oil up in the cyl with the fuel. In time this could cause hard starting due to plug covered in oil and muff can get plugged with wet carbon . Stick to manu. specs.

 

[5150abf]

Re: 100/1 or 50/1 oil mix

Mix it 100:1 and add a splash more, I always use a couple extra tablespoons of oil just because, you don't have to jump right to 50:1, doubling up on oil is kind of extreme but just a bit more will give you a little more oil but not enough to cause a problem, call it 90:1

 

[Sea Rider]

Re: 100/1 or 50/1 oil mix

What is your opinion about using a mix of 50/1 in a 3HP 2001 Yamaha 2 stroke, that has been produced to use a 100/1 mix. But is used a lot at full speed while pushing a 12 foot punt.

If you are using that small engine at wot most of the time, I would go for a 75:1 mixture, you generally foul plugs when at too much idle or trolling speeds when runing 50:1

Happy Boating