oil mixture

[Skip Silvestrini]

I have a couple of 1950’s outboards. In their day, they ran 24:1 oil to gas. One quart 30 weight automotive oil to 6 gallons of gas. Of lot of blue smoke and pollution. I’ve had two outboard mechanics tell me that with the development of dedicated 2 stroke oil with TCW3 as a standard, I could safely run at 40:1. The question is what is the difference between 1950’s outboards and 1960’s outboards that ran at 50:1? If running with dedicated TCW3 oil, why would the 1950’s engines need more oil?

Skip

[labrador-guy]

Oil/gas mixture is dependent on what motors you are running. Many OMC built motors built in the early 50’s have all brass bushings and they need a little more oil to live longer. One thing for sure DO NOT use automotive oils! They make carbon build up and will eventually clog up ports and exhaust passages. In my opinion use TCW3 synthetic oils. A little more oil is cheaper than buying parts. Plenty of members run 16 to 1 ratio. Myself I like 24 to 1. Mercury’s run all needle bearings and you would be alright with 32 to 1. Just my humble opinion!

dale

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Skip Silvestrini

[fleetwin]

Like LG says, it depends on the engine…. Using 24:1 on an engine with bronze bushings on the rods could result in a disaster, regardless of today’s improved oils, stick with the original 16:1 recommendation. Older engines with needle bearings would probably be “OK” with less than the 24:1 mix, but it is not worth the “gamble”. The beauty of the old OMCs is that when they are in good shape, and tuned properly, they don’t smoke much once started and warmed up, even with the 16:1 mix.
Tell us which 1950s OMCs you are running… Many of today’s younger techs have had little or no experience with the older outboards, they are just spewing the hype from the oil companies and manufacturers.

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Skip Silvestrini

[Skip Silvestrini]

I have a 1953 Big Twin and a 1954 Big Twin Electric (got tired of rope starting the ’53) and a 1972 Johnson 25R all of which push a 1952 Feathercraft Deluxe Runabout. The high and low speed needle bearings are brass on the 1950’s motors but aren’t moving parts. I didn’t have to tear either down much to get either running though the ’54 had a mouse nest in the exhaust but the cylinders were clean. They both run well on 24:1 and I’m not worried about saving money. By the mid-late 1960’s all OMC engines were running 50:1 and typically at 5000 to 5500 RPM where as the old Big Twins are only 4000 RPM. OMC quit recommending automotive 30 weight oil and recommended 2 stroke oil exclusively. The Johnson runs 5000 RPM, is a smaller block so one would think it’d need more oil but 50:1 is recommended. So the question for me is why? I don’t know if there is much difference in their construction which would make sense if there was. I had assumed it was automotive oil vs. dedicated 2 stroke oil which likely has superior lubricating properties. Especially since two different mechanics (both of whom work on vintage motors) both felt the motors could be run on 40:1 and that seemed arbitrary so thought I’d ask. I appreciate the replies.

Skip

[fleetwin]

The engines that I am referring to have plain bushings on the large end of the rods….None of the engines you mentioned have this set up. I am not concerned about the plain crankcase bushings as far as lubrication is concerned. I’m pretty sure the old Bigtwins had an original mixing recommendation of 24:1, so that is fine. The 72 25hp had a recommendation of 50:1, so that is fine.
Have oils improved since the 1950s, sure. In the end, these are your outboards to lubricate anyway you wish.

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Skip Silvestrini

[stanley]

1953-1954 Evinrude big twins and Johnson RDs specify 16:1

[Tubs]

A "Boathouse Repair" is one that done without having tools or the skills to do it properly.

2 users thanked author for this post.

stanley, Skip Silvestrini

[stanley]

That’s interesting Tubs.I was repeating what the original oiling instruction decals on my engines say.

[Tubs]

A "Boathouse Repair" is one that done without having tools or the skills to do it properly.

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stanley

[JOHN HOLBIK]

When OMC switched to 50-1 they made all the motors with fixed high speed .The snow mobile manufacturers learned this lesson in the seventies alot of engines were seized because the riders were leaning out the Tillitson carbs in an attempt to get a little more speed.

[Author]

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