50:1 fuel mix . . . is 40:1 better?

[catfighter]

So I understand that old motors say to use 100:1, but Johnson later says to use 50:1. My question is this: is it bad to use a lower ratio, say 40:1 mix? My motor is old (well, it's 27 years old; in outboard years i guess it's not THAT old), but I want to make sure that everything is being lubricated well.

BTW - I have a 1983 Johnson 15hp, model #J15RCTR

Just wanted to get everyone's take on the idea.

 

[the machinist]

Re: 50:1 fuel mix . . . is 40:1 better?

In my opinion the 50-1 may be even rich for that motor IF you use it for any trolling at all. As your plugs will foul a lot sooner using the standard TWC-3 oil. Better yet would be to use the 50-1 with a synthetic blend oil.

 

[Jeff_G]

Re: 50:1 fuel mix . . . is 40:1 better?

On some of the small engines OMC years ago determined that 100 to 1 was fine for use. The problem was it left no protection for engines sitting. There wasn't enough oil left inside for start up lubrication nor rust protection, so some motors rusted up over winter. OMC recended the recommendation, send some letters and service bulletins.
Almost all modern outboards call for 50 to 1 oil ratio. 40 to 1 is heavier oil and not needed unless you are running high reving or high performance engines. 50 to 1 is fine with all the engines out there. No manufacturer recommends less than 50 to 1.
A properly tuned and running engine should do fine on that ratio. If very extensive trolling or idling, particularly in cold climates, you may get more fouling but keeping on top of things will stop that or use a product like Mercury's Quickleen in the fuel. Todays gas although junk in many respects, does have additional detergents that will help. Just run a good quality TCW-3 oil, I would recommend a motor manufacturer brand.
Most engines running oil injection do run leaner mixtures at idle, but for a pre-mix engine run the 50 to 1.

 

[jeff_smith_0423]

Re: 50:1 fuel mix . . . is 40:1 better?

No manufacturer recommends less than 50 to 1.

Except Yamaha's portable 2-strokes which are recommended 100:1 on Yamalube. Don't know anyone who actually does it though.

 

[witenite0560]

Re: 50:1 fuel mix . . . is 40:1 better?

So, I've got a 1970 115hp Evinrude that's supposed to use a 50:1 mix and I have a 1960 10hp Scott that I want to put on as a kicker/trolling motor. The Scott sticker says it's supposed to have a 40:1 mix. I'd like to run them off a common tank. Will I be ok running the Scott on 50:1, with modern 2 cycle oils? Thanks.

 

[jeff_smith_0423]

Re: 50:1 fuel mix . . . is 40:1 better?

Probably be ok but best to check in the "Other Outboards" section to see if someone has experience.

 

[kbait]

Re: 50:1 fuel mix . . . is 40:1 better?

I've been running Amsoil Saber outboard synthetic 100:1 premix on all my 50:1 motors w/no problems whatsoever. I do fog 'em before storage, to prevent them from rusting up. Never fouled a plug!

 

[jeff_smith_0423]

Re: 50:1 fuel mix . . . is 40:1 better?

that's a whole separate ball of wax, here.

 

[F_R]

Re: 50:1 fuel mix . . . is 40:1 better?

So, I've got a 1970 115hp Evinrude that's supposed to use a 50:1 mix and I have a 1960 10hp Scott that I want to put on as a kicker/trolling motor. The Scott sticker says it's supposed to have a 40:1 mix. I'd like to run them off a common tank. Will I be ok running the Scott on 50:1, with modern 2 cycle oils? Thanks.

Do you know that Scott-Atwater/McCulloch originated the oil mix war when they said to use 100:1 (with their oil)? I'm just tossing that in for thought, not saying to do it.

One pint of oil to 6 gallons of gas is actually 48:1. And how often to you go to fill a 6 gallon tank and find it isn't completely empty and won't take the whole 6 gallons. In other words, they are often run on closer to 40:1 than 50:1. Don't worry about it, it will be fine as long as you don't try cheating with less than 50:1.

 

[Cricket Too]

Re: 50:1 fuel mix . . . is 40:1 better?

I would think those older small engines, like the Scott, spec'd 40:1 because of the oil technology at the time. TC-W3 is leaps ahead of what was available back in 1960, and will protect a lot better, even with a leaner mixture.

In fact I bet a 50:1 mixture will protect that Scott better than a 40:1 mixture with 1960's oil did.

The only thing I ever owned that required a 40:1 mixture is my McCulloch chainsaw.

 

[witenite0560]

Re: 50:1 fuel mix . . . is 40:1 better?

FR and Cricket, I think we're on the same page. Thanks for the input.

 

[catfighter]

Re: 50:1 fuel mix . . . is 40:1 better?

You people hijacked my thread!

lol j/k, I was just generally interested in what people thought of this. I'm with F_R, too. Who actually measures out EXACTLY 50:1? it's probably somewhere between 40:1 and 50:1, which was actually why I posed the question in the first place.

 

[jeff_smith_0423]

Re: 50:1 fuel mix . . . is 40:1 better?

Who actually measures out EXACTLY 50:1?

This guy.

But then again, I buy my boat gas 2.3 gallons at a time (25hp tiller).

 

[Milemaker13]

Re: 50:1 fuel mix . . . is 40:1 better?

Its so funny to find you guys talking about this. I guess I already have my awnser.

I'm going to run my "new" 25 hp Evinrude today and take it out tomorrow. Its a 1976 if I remember correctly. So, the same 50:1 gas is the way to go? Thats great, I can just use the gas from the '58 10 horse.

I also agree, they used to use regular 30 wt engine oil in the gas. Now we have much better oils. Thanks guys!

 

[Patate]

Re: 50:1 fuel mix . . . is 40:1 better?

@mile

Your 58 10 hp is supposed to run on 25:1 i think...

 

[jeff_smith_0423]

Re: 50:1 fuel mix . . . is 40:1 better?

@mile

Your 58 10 hp is supposed to run on 25:1 i think...

I was going to make the same comment.

 

[Milemaker13]

Re: 50:1 fuel mix . . . is 40:1 better?

Really? Help me out here... What is one quart of oil into 6 gallons of gas?

 

[Sea18Horse]

Re: 50:1 fuel mix . . . is 40:1 better?

That's 24:1 (or 25:1 if you want to round up ). Just right for your 10 horse. Maybe a bit richer than necessary for your 25 horse. You'll have to decide for yourself if the smoke is too much. And see if you foul plugs excessively. 48:1 (50:1) would be better but then you'd have to keep track of two different tanks. Easy if your 10 horse still runs the pressure tank.

Cheers....................Todd

 

[catfighter]

Re: 50:1 fuel mix . . . is 40:1 better?

1 gal of gasoline = 128oz

6 gals of gasoline = 768oz

768 / 16 = 48:1 ratio.

 

[pecheux]

Re: 50:1 fuel mix . . . is 40:1 better?

Do you know that Scott-Atwater/McCulloch originated the oil mix war when they said to use 100:1 (with their oil)? I'm just tossing that in for thought, not saying to do it.

I owned one of those 9 hp McCulloch while there was still a dealer in my area. Their 100:1 McCulloch oil was colored red and was a special animal. To the touch it was ultra slippery and seemed to be a lighter grade oil than their 50:1 Never seen anything like it since.
Also in comparison to some other brand 100:1 rated oil McCulloch's waranty was covered no matter which oil you choosed as long as it was THEIR oil. At that time the mix was 50:1 It may be that way back when those engines were called Scott Atwater (I knew dealer) the recommended ratio might have been 40:1 which made those motor ahead of their time since most other OB's called for 24:1

Oups ... I just noticed this is a way old post ..