Oil ratio for a Scott Atwater 16

[kerry]

Listen to Pappy. Its not the quality of oil, its the QUANTITY you need. Tolerances were larger back then, because that was what their machinery was capable of. No CNC, robotic, laser, etc. Quantity of oil was needed to keep metal from hitting metal. Synthetics keep a film of oil on parts better than conventionals, but I would not lean the ratio too much. Pennz full synth is around $27 a gallon near me, I believe the low smoke and 100% biodegradable are worth it.

If you have too many, AND not enough, you're a collector.

[billw]

Oh brother. I hate being the dumb one, when smart people are telling me two, opposite things! I guess the real questions are these: Will there be less oil sheen on the water with full ratio synthetic and does a Scott 16 really need 16:1???? One thing is certain. My Scotts are not ever going to wear out if I can’t run them…..

I will say that if I were from a time when people believed that the sun revolved around the earth and then I was told that the earth revolved around the sun, I would never change my view. In the Revolutionary War, I would have sided with the King. I thought carburetors would be better than fuel injection. I would never, ever think about using synthetic, when dino has worked for me for 50 years of boating, were it not for the yacht club perception thing…and no WAY am I going to use it in a "valuable" engine;" so I’m not worried about submitting a warranty claim….

Long live American manufacturing!

[Casey Lynn]

quote BillW:

and does a Scott 16 really need 16:1????

And after all of that you are asking the same question again? I give up!

[Tubs]

>

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

• This reply was modified 6 years, 8 months ago by Tubs.
• This reply was modified 4 years, 4 months ago by Tubs.

[billw]

quote Pappy:

quote BillW:

and does a Scott 16 really need 16:1????

And after all of that you are asking the same question again? I give up!

Yeah, I think I give up too.

Long live American manufacturing!

[jim-moffatt]

deleted

[jim-moffatt]

On May 3 1963 Scot issued service bulletin 352. In that they state that pre 1961 motors with full roller bearings can be run 40:1 with what was then Scott premium outboard oil. So, I will go out on a limb and say try 40:1 with either TCW3 or full synthetic. (See my other tests in an earlier post)

THIS WAS SCOTT’S PUBLISHED RECOMMENDATION.

[Casey Lynn]

quote Jim Moffatt:

I will jump in the fray. I have been running a 1932 Fleetwin that was rated a 1 pt per gallon on 6oz per gallon of full synthetic. After each run I check the cylinders for condition with an internal light. Not only is there no scoring but there is a healthy film of oil all around them. MY tentative conclusion is that this ratio works well on all similar hp opposed piston engines. I realize that this is risky but I started with short runs and gradually lengthened them. I plan to continue.

For a long time I have been trying to find lubricity values for ordinary motor oil and twc 3 or ful synthetic oil. I just cant find them.

So let me get this straight.
You did not measure the bore to establish a reference point prior to your "Testing".
You did not measure the piston at the dome and skirt prior to your testing.
No photos of the piston skirt area on the thrust side for reference that you can check for change.
Your method is to simply look at the cylinder wall and see if it is scored.
And from this you are making a blanket statement that a lean ratio is okay for folks to run?

[jim-moffatt]

I deleted the post above and put it in dockside so members can discuss it.

I dont recommend this to anyone. Its just the results of my testing. There are no marks on the thrust side of the cylinder and lots of oil there.

There is no way to verify this except that the Scott recommendation that roller bearing engines can be run leaner than 16:1 if TCW3 or higher quality oils are used. I will not go below 6 oz per gallon.

[billw]

Thanks Jim. This is the reason I "asked the same question again." I suspected someone might have an answer to it. If Scott issued a bulletin for 40:1 in place of 16:1, then it must be similar to OMC saying you could use 50:1 where they used to call for 24:1. I am well aware that you can’t do that on bushed engines, but let’s say a 1956 15 OMC would run just fine on it. I suspected that MIGHT also be the case with certain Scotts and the 16 hp ratio seemed crazy. Heck, even if I can run it on my usual 24:1, that I use for my other full bearing engines, I will be happy. Thanks again.

Long live American manufacturing!

[Author]

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