oil fuel ratio

[dj7]

There is a decal on my 1964 Evinrude 3 HP Lightwin that calls for 50:1, but I got 24:1 from another source. Which is correct?

 

[rickdb1boat]

Re: oil fuel ratio

40:1 would be correct for the smaller motors that year. Some still had bronze bearings that required the richer mix..

 

[JB]

Re: oil fuel ratio

1964 was the first year that OMC called for a 50:1 mix in all OMC engines, but, as Rick points out, the 3hp engines had not yet converted to all frictionless (ball and needle) bearings.

Because the engines were unchanged from the 1963 and earlier (24:1) engines I recommend using 24:1.

A 40:1 mix will probably work. A 24:1 mix will certainly work.

 

[pecheux]

Re: oil fuel ratio

I owned a few OB within those years when Omc fist came out with the 50:1 ratio and I had to debate this subject with my dealer.

At that time for 24:1 mix ratio motor they recommended using either 32:1 for older OB,s and 40:1 for those newer ones ... BUT that's with using 50:1 type oil.

Obviously there is no more 24:1 type oil on the market so I would probably use a 32:1 mix.

 

[JB]

Re: oil fuel ratio

There is no "24:1" type oil and there is no "50:1" type oil. Mix recommendations are based on the engine requirements and the requirements to use a specified oil spec. You will not find a spec to mix 24:1 with automotive oil or 50:1 with TC-W oil.

OMC's change from 24:1 to 50:1 in mix recommendations was mostly based on their changeover to mostly "frictionless" bearings on most of their engines and only partly on the requirement to use TC-W certified oil.

History (43 years of it) has shown that using 50:1 in the 3HP engines built before 1970 shortens their life. I don't know that using 30:1 or 40:1 would do so also, but I am sure that using 24:1 will not.

 

[pecheux]

Re: oil fuel ratio

There is no "24:1" type oil and there is no "50:1" type oil. Mix recommendations are based on the engine requirements and the requirements to use a specified oil spec. You will not find a spec to mix 24:1 with automotive oil or 50:1 with TC-W oil.

OMC's change from 24:1 to 50:1 in mix recommendations was mostly based on their changeover to mostly "frictionless" bearings on most of their engines and only partly on the requirement to use TC-W certified oil.

History (43 years of it) has shown that using 50:1 in the 3HP engines built before 1970 shortens their life. I don't know that using 30:1 or 40:1 would do so also, but I am sure that using 24:1 will not.

You have a point that cannot be argued with the 24:1 safety in that particular motor.

Nevertheless when johnson and others produced motors that worked with the 50:1 ration I was filling approx 80 five galon tanks a day true the summer months at my dad's garage (near a river) and some wanted 24:1 others the 50:1 blue oil.

On each container was writen the following:

24:1 quarts (gold oil) = for mixing up to 24:1 ratio
50:1 pints (blue oil) = for mixing up to 50:1 ratio

So I figured there was a difference either with the oil itself or with the additives, and since my omc dealer confirm it with me ... I had no reasons to argue. They (omc) are the one (at that time) recommending the 32:1 (50:1 blue oil) in older engines.

I refuse to stop learning ... keep me informed. Tx

 

[JB]

Re: oil fuel ratio

Hmmmmmm. Well, the oils were clearly different colors and it is reasonable to believe that they were different in other ways, too.

Were they both TC-W2 certified oils? What brand(s)? I think TC-W2 was available at that time (early 60s). Or could the gold oil have been TC-W and the blue oil TC-W2?

I think you may have generalized instructions for one brand at one time to all brands at all times. I have been using and messing about with outboards, mostly JohnnyRudes, for nearly 60 years and this is the first time I ever ran into what you are telling me.

 

[Snowdrggn]

Re: oil fuel ratio

I have a 1976 4 hp Evinrude model 4606, I am under the understanding that it still has a bronze bushing at the top of the crankshaft. Is this true?
What ratio would be a good idea to run it at?

thanks for the input,
Snow.
I have been using 40:1

 

[pecheux]

Re: oil fuel ratio

Hmmmmmm. Well, the oils were clearly different colors and it is reasonable to believe that they were different in other ways, too.

Were they both TC-W2 certified oils? What brand(s)? I think TC-W2 was available at that time (early 60s). Or could the gold oil have been TC-W and the blue oil TC-W2?

I think you may have generalized instructions for one brand at one time to all brands at all times. I have been using and messing about with outboards, mostly JohnnyRudes, for nearly 60 years and this is the first time I ever ran into what you are telling me.

Our conversation forces me to think back a few years ... (lol) and I am enjoying this ... not for argument sake but strikly for sharing information, I now remember the reason behind my omc dealer's suggestion.

She (was a lady owner) had mentioned that the 50:1 type oil had someting like a higher flaspoint than the 24:1 type oil and therefore would foul up the spark plugs when used at a 24:1 ratio.

In addition she had mentioned that because of the higher lubrificacity of the 50:1 oil over the 24:1 oil it was considered safe to use the 50:1 oil in an engine originaly designed for a 24:1 mix type oil ... at a 32:1 ratio.

At that time our family business was under the Esso sign so we sold Esso OB oil. the 24:1 came in quarts, the 50:1 came in pints. Obviously Omc had their own brand.

That's all I know from Omc. I am not a mecanic by far, I play with OB motors (love em) and do maintenance. I have a good friend who is an ex Merc dealer and mecanic so I turn to him for real repairs. LOL

Have a great day.

 

[JB]

Re: oil fuel ratio

Thanks for that info, Pecheux. It makes several things clear.


I would feel free to run 50:1 in your '76 'Rude, Snow, but I am sure 40:1 is safe.

 

[Chinewalker]

Re: oil fuel ratio

The '76 has a needle bearing at the top main, but bronze everywhere else. Running it a bit fatter will not hurt. Running it lean could... I've got a pile of the 1970s 4hp blocks with holes through the sides where rods sought daylight...
- Scott