Oil/gas mix

[cc67]

Why do the older outboards use 24: to 1 ratio and the newer ones, (reletively speaking), use a 50: to 1 mix. What is the difference in the motors?

 

[BoatBuoy]

Re: Oil/gas mix

There's lots of differences in the later motors that are not apparent - bearing size and material being two. Older outboards used friction bearings in some cases. Later models use roller/needle bearings. The later bearings are also much harder. In some of the older models, oil was also used to assist in sealing the crankcase at the crank. Another difference is that the piston ring configuration of older motors was to have three wide piston rings rather than the two narrower rings used now. More rings means more friction.

Edit: I asked this same question a while back and Chinewalker was kind enough to explain it to me, so I'm just passing it on.

 

[cc67]

Re: Oil/gas mix

So would a 57 Evin/John with the 22 cu in motor use the richer mix? I was looking at a older Evinrude 18 hp and wanted to know what year they changed the mix.

 

[tashasdaddy]

Re: Oil/gas mix

early 1950's from 16-1 to 24-1 then 50-1 in 1964 on most of them.

 

[JB]

Re: Oil/gas mix

In 1964, after the introduction of TC-W rated oils, OMC changed the recommended mix for all pre-1964 OMC-made engines to 24:1 using TC-W oil and recommended 50:1 for all 1964 and later OMC-built engines.

This move did not exactly coincide with complete changeover from sleeve bearings to "frictionless" ball, roller and needle bearings, but it did exactly coincide with other design changes anticipating a 50:1 mix.

There are pre-1964 engines that can satisfactorily use a 50:1 mix and 1964 and later engines that probably are safer using a 24:1 mix, but I am unaware of any engine failures directly due to following OMC's recommendations.

I therefore stick to what OMC said in their 1964 Service publications. I use 24:1 with TC-W3 oil in my 1948 Gale-made Sea King 1.5.

 

[pecheux]

Re: Oil/gas mix

In 1964, after the introduction of TC-W rated oils, OMC changed the recommended mix for all pre-1964 OMC-made engines to 24:1 using TC-W oil and recommended 50:1 for all 1964 and later OMC-built engines.

This move did not exactly coincide with complete changeover from sleeve bearings to "frictionless" ball, roller and needle bearings, but it did exactly coincide with other design changes anticipating a 50:1 mix.

There are pre-1964 engines that can satisfactorily use a 50:1 mix and 1964 and later engines that probably are safer using a 24:1 mix, but I am unaware of any engine failures directly due to following OMC's recommendations.

I therefore stick to what OMC said in their 1964 Service publications. I use 24:1 with TC-W3 oil in my 1948 Gale-made Sea King 1.5.

I'm with you all the way ... and was backed by an Omc dealer (a friend) but then I wrote similar information on another post and got blasted. Problem is many OB owners dont realise the BIG difference in the oil itself from the 24:1 type oil VS the 50:1 type. Nevertheless if I had a 1948 OB I would probably bring the mix down to 40:1 (as per my omc friend's suggestion)

 

[JB]

Re: Oil/gas mix

You misunderstand what I wrote, pecheux. There is not a "24:1" oil and a "50:1" oil. The differences that call for 24:1 or 50:1 are in the engines. OMC engines that were made for 16:1 using SAE-30 motor oil can run 24:1 with TC-W3.

The 24:1 recommendation for pre-1964 engines calls for the use of TC-W oil. That is currently TC-W3 but might be TC-W4 in the near furure.

If you try running a 1948 Sea King on 50:1 or 40:1 you are asking for trouble, even if it is TC-W3 oil.

 

[cc67]

Re: Oil/gas mix

The reason I posted this question was that there are a few late 50s John/Rude motors for sale around here and I thought it would neet to have one. We all know that oil today is better than oil was 50 years ago. So that being said I thought I could use the same 50:1 mix that I use in my 66 Johnson 20hp in say a 58 Evinrude fastwin. Apparently not.

 

[Chris1956]

Re: Oil/gas mix

CC67 - Some of the pre-1964 OMC engines had all roller bearing design, and are suitable for a 50::1 mix. Joe Reeves is likely the best source of the models that meet this criteria, since he has first-hand experience.

If you are planning on buying a pre-1964 25+HP OMC, you might check with Joe to see what mix ratio he recommends.

 

[pecheux]

Re: Oil/gas mix

You misunderstand what I wrote, pecheux. There is not a "24:1" oil and a "50:1" oil. The differences that call for 24:1 or 50:1 are in the engines. OMC engines that were made for 16:1 using SAE-30 motor oil can run 24:1 with TC-W3.

The 24:1 recommendation for pre-1964 engines calls for the use of TC-W oil. That is currently TC-W3 but might be TC-W4 in the near furure.

If you try running a 1948 Sea King on 50:1 or 40:1 you are asking for trouble, even if it is TC-W3 oil.

Yes I misread the last few lines of your post ... sorry. Nevertheless I know for a fact, and straight from the horse's mouth that the 50:1 (blue) type oil and the 24:1 (30w) type oil are two different beats and that OMC back then promoted the idea that pre 64 OB could be used at the 32:1 mix ratio conditionaly that the oil would be of the 50:1 type (blue)

The horses happened to be my uncle who was an oil expert for Veedol than later Castrol, the other was a friend who was an OMC dealer. Back then I was pumping and mixing gas/oil all weekends for a marina next to my dad's garage and I did withness the phasing out of 24:1 type oil, and it's replacement by the new 50:1 type oil ... mixed at 32:1 for most pre 64 OB's.

Not looking for an argument here ... just sharing, and nobody has to agree with me ... we'll still be friends ... LOL

 

[JB]

Re: Oil/gas mix

My information is straight from the Johnson Service Manual, tenth edition. It spends several pages explaining why all pre-1964 engines should use a 24:1 mix, then simply says that 1964 engines can use a 50:1 mix after break-in with 24:1.

I realize that not all models changed engineering specs at the same time, but recommending that someone go against the recommendations of the people who designed the engines seems irresponsible to me.

That is why I think you are using the correct mix in your 1966 engine, cc67, but it would be the wrong mix for a 1958.

 

[pecheux]

Re: Oil/gas mix

My information is straight from the Johnson Service Manual, tenth edition. It spends several pages explaining why all pre-1964 engines should use a 24:1 mix, then simply says that 1964 engines can use a 50:1 mix after break-in with 24:1.

I realize that not all models changed engineering specs at the same time, but recommending that someone go against the recommendations of the people who designed the engines seems irresponsible to me.

That is why I think you are using the correct mix in your 1966 engine, cc67, but it would be the wrong mix for a 1958.

Nothing wrong in being "by the book". I simply remember when the 24:1 outboard type oil became Nla and only the 50:1 type (blue) oil was available labelled for outboards. At that time (quite a while ago lol) most OB owners had to either go for the 30w that also became Nla or go for the (then) new 50:1 type oil ... no matter what mix ratio they choosed. No argument here since we are comparing books with experience ... and two rights dont have to equal one wrong ... LOL LOL

Note: Oil type availability have always been leaner on this side of the
border (Canada)

 

[cc67]

Re: Oil/gas mix

My information is straight from the Johnson Service Manual, tenth edition. It spends several pages explaining why all pre-1964 engines should use a 24:1 mix, then simply says that 1964 engines can use a 50:1 mix after break-in with 24:1.

I realize that not all models changed engineering specs at the same time, but recommending that someone go against the recommendations of the people who designed the engines seems irresponsible to me.

That is why I think you are using the correct mix in your 1966 engine, cc67, but it would be the wrong mix for a 1958.

Good information, Learn something new every day.

 

[Chris1956]

Re: Oil/gas mix

Folks, SAE-30 non-detergent automobile oil is what was used in outboards prior to the TC-W family of oils. This oil is still around, although not every store carries it. Since it is not dyed, it is hard to tell if the gas has been mixed with this oil

One could use this "old" oil successfully in sixties and earlier outboards, however the TC-W oil is superior in reducing carbon buildup and other advantages.

 

[pecheux]

Re: Oil/gas mix

Yep ... SAE-30 non detergent automobile oil ... with LOTS of additives added to it for proper mixing prior to calling it Outboard oil ... G

 

[steelespike]

Re: Oil/gas mix

In looking at older after market repair manuals it appears the clearances and bearing specs are identical for the 66 22 cu in 20hp motors and the 57 22 cu in 18 hp motor.The same manual clearly specifies 24:1 to 63 and 50:1 64 on.
I would reluctently consider 50:1 for those older motors though actually using it in my own motor would take a lot of thought.I absolutely would not run 40:1 in the old 16:1 motors but would run 24:1.It would interesting to see Scotts(chinewalkers)take on this.

 

[Chris1956]

Re: Oil/gas mix

Steel, can you tell if the older motor had all roller and ball bearing design, or did it have some brass bushings? That difference is what seperates the 24::1 from the 50::1 motors!

Drop a note to Joe Reeves. He can advise you on the proper oil-gas mix.

 

[steelespike]

Re: Oil/gas mix

Steel, can you tell if the older motor had all roller and ball bearing design, or did it have some brass bushings? That difference is what seperates the 24::1 from the 50::1 motors!

Drop a note to Joe Reeves. He can advise you on the proper oil-gas mix.

According to the after market manual the the 22 cube 57 has the same number of roller bearings as the 66 motor and it appears ring end gap and side clearence etc. are the same.The sofistication of the bearings isn't discussed.It does appear that other components are very similar thus the same clearances.When I refer to older motors needing 24:1 I refer to any motor that isn't 100% "Jeweled"Even the somewhat more modern 6hp E/J
motors rated at 50:1 can have premature failure.These 69-79 motors appear to have only the crank pin as a roller bearing.If these motors experience occasional failure I think those of older technology would be at greater risk.

 

[Chinewalker]

Re: Oil/gas mix

The main reason I would NOT use a 24:1 ratio in the 1957 18hp is that it is NOT thermostatically controlled for cooling. With that the case, the tolerances involved can vary a great deal more than the 1966 version. Sitting on the bench, the ring end gap may be the same, but when underway and things start expanding and contracting at different rates, those tolerances change. A statted motor can control those variations within a smaller window a lot better than one that is not statted...

This is the same reason I would not use 50:1 in any of my pre t-stat OMCs, regardless of the number of needle and roller bearings in use.

- Scott

 

[JB]

Re: Oil/gas mix

Now I am confused, Scott.

Did you mean that you would NOT use 50:1 in the '57 18HP?

Your explanation seems to be why to use 24:1 in the non-t'stat engines and 50:1 only in temp controlled engines.