Commando 500- oil mixture suggestions?

[Dumbo812]

Picked up a Commando 500. Some numbers off of a plate on frame T-642-04-c #6237971. Sticker with serial number#2174. Has a Techumseh Motor #610715. From what I found online it appears to be from 1970 and is 5hp.

I does not have its own tank on the motor and before I spent money on a fuel tank and line, I rigged a siphon ball line from a 1 gal gas can directly to the carb fuel inlet. I used my 2 cycle mix that I have for gas trimmer and gas blower. The oil mix used was a synthetic 2+ oz bottle that can be used for any oil gas mix. It says on the bottle from 16:1 all the way to 50:1. I have used this oil for the past year in the trimmer and blower with no issues. One takes 40:1 and the other 50:1 so this oil saves me from having to keep two different cans laying around. So on the outboard I cleaned out the carb, put in a new plug, rig the gas line and it fires up. Ran it for about a minute with the gas mix I had. The motor sounded and ran great.

Then I invest in the gas can and gas line. Hunt around for the proper connector to attach to motor quick connect. The motor has a sticker that says to mix the oil 16:1. I asked the guy at the marina what he thought and he suggested 32:1 with marine oil since oil is better than it was in 1970. Not wanting to seize this motor before I get out on the water I started with 16:1 mix. I could get it to start but it didn't sound good, laboring and then dying out. So I added more gas to mix 24:1. a little better but still seems like its running rich. Now I have up to a 32:1. It started up and ran for a few minutes but it didn't seem as strong as when I had the original "all in one" mix I use with my other 2 cycle motors.

From what I have found online some say to use only Marine Oil and others say this old motor is nothing more than an old 2 cycle chain saw motor that should use your basic 2 cycle oil mix.

Any thoughts on what oil to use and ratio suggestions?

 

[F_R]

Well, for some background, yes it is a chainsaw engine adapted to an outboard. And as chainsaws, they ran on 16:1. But I'm surprised that it is stickered to use 16:1 on your motor. Sometime around that time period they decided 50:1 was ok.

Now, you will get all kinds of opinions and you can pick the one that suits you best. Personally, those things run so hot, that I can't see how they survive on 50:1, but I guess they do. I wouldn't do it if it were mine. And yes, because of the heat, I'd use chainsaw oil.

Just my 2c. Add another $2 and you will have enough to get a cup of coffee at the gas station.

 

[Dumbo812]

Thanks FR- Has anyone tried or heard of running all-in-one mix ratio 2 cycle oil in these motors? I was looking to try Amsoil Saber 2-cycle mix. That one seems to be the best in the 2-cycle motor forums for chainsaws, blowers, trimmers, etc.

 

[steelespike]

My aftermarket service manual says clearly to use a good outboard oil at 16:1
Manual also states various 2 stroke oils may be used as a substitute avoiding detergent oils
even suggesting straight SAE 30 weight.
The mix ratio has little affect on performance except for the amount of smoke.
Definitely don't lean out the mix.
A good grade of TCW3 rated oil is fine.I have a bottle here suggesting use in
every 2 stroke application you could think of including outboards,snowmobiles,motorcycles and
chain saws etc.
3 versions of the Tecumseh motor were used V51,V61 and V81 5.1 cu in,6.1 and 7.98.
1 5/8 stroke,1.769 and 1.625.Models called Commando V,VI,VII, all 4 hp.It does appear
logical your's is a 5.
The V61 has a removable head the others a one piece cylinder and head.
The V51 was specifically designed for outboard application
I have several manuals covering back to 55. My Commando information is from 61-67 in the 55 up manual
it doesn't appear in my later manuals.