Cheating with synthetics?

[shoestringmariner]

Hey folks, what are the odds I can lean out the mix slightly when using a synthetic oil? I have 2 old OMCS that are both (to my knowledge) 16:1 motors (5hp johnson and 7.5 Fleetwin)

I was told the Evinrude XD was good oil to use to get the smoke down, but in order to avoid dealing with the supreme clown at the local Evinrude dealer, I picked up some Amsoil HP marine oil. I am wondering with today’s synthetics if I can cheat the ratio ever so slightly…say 20:1 so I can fill a full 10l can per half lite of oil. Does anyone think this is pushing my luck?

[david-bartlett]

check your PM

[Mumbles]

Why take chances and vary from the original 16:1 recommendation? Sure, those motors will run on 24, 32, or even leaner mixes but for how long? If they are trolling all day long, a leaner mix will work but they really do need the extra oil for high speed operation because of the sleeve type bearings on the crankshaft. Some extra TCW III oil in the fuel mix is a lot cheaper than trying to find NOS parts to rebuild your motor and if you run it hard, you shouldn’t notice any excessive smoke behind your boat. If you are thinking of the full synthetic Evinrude XD100 oil, save your money as it’s designed for the E-TEC motors which can be programmed to use it at leaner than normal ratios.

[PugetSoundBoater]

I agree with Mumbles. Oil is cheap, save the bearings. Read the labels on the OMC oils ,what motors they are designed for.
I try to minimize the excess oil getting discharged into the water. Keeping the ignition system in good condition, good plugs in it and adjusting the well functioning carb to the best settings will help reduce excess oil discharge and smoke.
It is a 2 stroke after all.

"Some people want to know how a watch works, others just want to know what time it is"
Robbie Robertson

[RICHARD A. WHITE]

I love these conversations. I, as a test last night, went to take my newly acquired ’56 Johnson 15 hp electric start for a cruise. Now I have been saying for years I will try that danged synthetic, so I bit the bullet bought one 16 oz bottle of synthetic blend. Now by my calculations or so on my mixing bottles calculations that should have been 24:1 if mixed with 3 gallons of gas. poured the oil in the tank, then pumped 3 gallons of fuel, shook it well and went to the lake.

I am super paranoid as I saw absolutely NO smoke, this scares the living hell out of me, but it is the correct mixture.

So I guess my response to your question would be, mix the synthetic at recommended ratio and let it go, don’t try to skip, and your motor will thank you.
We have a meet over in Ohio this weekend and I plan on using this motor for that ride, so I will know more, but I cant think of any reason to use the normal oil if this will lubricate and NOT smoke, then what do they have to complain about.

Take care

Richard

http://www.richardsoutboardtools.com
classicomctools@gmail.com

[crosbyman]

smoke is good for blackflies !
https://www.youtube.com/watch?v=qjLBXb1kgMo

Joining AOMCI has priviledges 🙂

[fisherman6]

I agree with everyone else above and in no way recommend cheating the gas oil mix on the dry side. I will, if anything, lean the other direction and mix mine on the sweet side. I usually run my 50:1 motors on 40:1 unless they have some plane bearings in them, then they get 32:1. My 24:1 motors often get 16:1 right along with the 16:1 motors. I run a semi synthetic blend TCW3 oil that claims to have low toxicity and it smokes very little even at 16:1 once the engine is at operating temperature. I’m not saying I’m right but this is how I run my motors and it works for me. More oil in the mix can’t do anything but extend the service life of the engine. The only oil these 2 strokes get is what collects on the parts as the mixture passes through the crankcase. Too many motors have been destroyed by not using enough oil in the fuel mix.
-Ben

OldJohnnyRude on YouTube

[vintin]

quote Richard A. White:

I love these conversations. I, as a test last night, went to take my newly acquired ’56 Johnson 15 hp electric start for a cruise. Now I have been saying for years I will try that danged synthetic, so I bit the bullet bought one 16 oz bottle of synthetic blend. Now by my calculations or so on my mixing bottles calculations that should have been 24:1 if mixed with 3 gallons of gas. poured the oil in the tank, then pumped 3 gallons of fuel, shook it well and went to the lake.

Take care

Richard

What percentage of the synthetic blend is actually synthetic?

I bet it is a small percentage or else it would cost a lot more.

[RICHARD A. WHITE]

I can look at the package, but not sure it will tell

http://www.richardsoutboardtools.com
classicomctools@gmail.com

[PM T2]

It may be only because I’ve been around so long, but I’ve seen about 800 forms of basically the same synthetic oil questions, and almost as many varieties of hopping about by the folks trying to answer it.

All I can suggest is that IF it is a true synthetic (i.e. Amsoil) then you are safe in reducing the quantity of oil used. Member Bill Salisbury did extensive testing (literally decades ago) using Amsoil in Elto Speedsters and Quads running at high (over 3000) RPM. He ran those motors as lean as 32:1 using Amsoil two-stroke oil and regular pump gas. His conclusions were that the motors were well protected at those ratios, and compression actually improved and top RPM increased as the hours of running time were logged and accumulated. He never experienced an engine failure or component breakdown running Amsoil at those ratios in genuine antique engines, so I’d have to suggest that you can cut your oil down some in a classic and it will be fine, provided it’s not a worn-out rattling hunk of junque to begin with. I’d be so bold to say that if you run a classic Evinrude or Johnson at 32:1 on pure synthetic oil and manage to blow it up, you had other problems that weren’t detected or fixed properly.

The last time I priced oils, the synthetics were about twice the cost of petroleum based oil. Since (if I recall correctly) you are being directed to use about "half" of the amount of oil with synthetics versus conventional TCW’s, the cost ends up being more or less a wash. To me, if you’re going to buy synthetic oil and continue to mix it at factory (heavy) ratios, then you’re sort of defeating part of the purpose of using a synthetic by doubling the cost of your oil supply.

If its a "synthetic blend", is this suggesting its a percentage of synthetic mixed with petroleum based oil? I guess you need to know that for sure.

FWIW I don’t bother with synthetics. in fact, I’m still working through a large stash of TCW2 oil, and it smokes like crazy compared to the TCW3. Part of the reason I like running these old things is to make smoke like they used to! getting rid of the smoke gets rid of half the fun.

Hope this helps.

Best,
T2

He's livin' in his own private Idaho..... I hope to go out quietly in my sleep, like my grand-dad did..... and not screaming, like the passengers in his car...

[Author]

Posts