How Old is too Old for 2 Cycle Oil?

Er, how old is too old for the pull-cord?

There are many other possible causes of an engine not starting that are higher up the list than the 2-stroke oil being in storage.

How old is "old"?

If it is a couple - three years old and the oil is clean, dry (no water contamination) and not separated you should be good to go.

If it is 4+ years, I would turn it in at a recycler and head over to the local Marine or auto parts store and buy a fresh bottle.

There's no expiration date on 2-cycle oil..

almost all outboards that old had a 25/1 gas to oil ratio. the motor will run lean and will lead to major damage using a 50/1 ratio.

Long ago I had a couple of 3 cylinder two stroke DKW cars[Last one was a 1960 model] which was supposed to have an SAE 50 strait engine oil mix of 40 to 1. I ran all of them on old motor oil drained from 4 stroke engine sumps. I even fitted one of these engins to my "Steyr Daimler Puch Haflinger" 4x4.

I just filtered the oil and did not use the bottom oil from the storage container. The same oil was used for my old 2 horse power seagul outboard engine but the mix was 10 to one.

It does not matter how old the oil is; Just shake the container a bit!

Thanks for all the answers.

And yes I changed the fuel oil ratio to 25:1. Easier to replace fouled plugs than the whole engine.

And I decided not to trust the old 2 cycle oil. It not that expensive. So I bought a few new quarts. Just have to find some way to dispose of the oil properly.

Simply add a few ounces of it at a time to the fuel of a high usage vehicle. 4 to 6 oz. per fill up should do just fine. If diesel, you can use more than that. try 12 oz. per fill up. Or you could bring it to the auto stores that recycle old engine oil.

Didn't know the stores that recycle regular oil would take the 2 cycle type.

They don't take coolant in my area. I have to wait until the local county govmt. has their disposal days to get rid of it.

If you poured it into the container used for used motor oil, there should not be any objection. That oil you have will require less work to convert back to usable motor oil than the crap I bring them.

It is not like you were bringing them plutonium.

you only need to check oil viscosity depending on how regular you run the engine. atleast start it once week/month.

I'm a Rum drinker myself. It is not the oil that gets old it is the additives, like EP, Viscosity modifiers, Anti-wear, Rust and Oxidation Inhibitors, Detergents.

Somebody make me shut-up, this could go on forever...

P.S. 2 cycle oil has to have good Hydrodynamic and Elastohydrodynamic properties... Don't fry your outboard.

When in doubt, don't use it. It may not hurt anything, however since the question has come to mind, it might be a good idea to get a new bottle and not have to worry if it's going to gum up the works.

How old was the oil when they pumped it out of the ground? The components of gasoline were the same age when they were pumped out of the ground, however, after refining, the gasoline contains more volatile compounds that will evaporate (most gas cans are not airtight) and leave the gas 'dead'. I don't think that the age of the oil is an issue.

As others have said, water contamination is another issue, but you didn't indicate any abnormalities.

The mixing ratio is very important, I once had an outboard that called for a 16:1 ratio. I have been told by outboard racing enthusiasts that they use more oil, than the engine originally called for. They liked the extra lubrication, and put up with the extra carbon fouling.

As in many other areas of life, a little extra lube is a good thing. Especially when old parts are rubbing together.

Unless subjected to heat and cold cycling, I do not believe the oil will go bad. It may have its additives drop out of suspension, but shaking should cure that. But, 2 cycle oil has seen some upgrades, and improvements. Would the newer formulations be better protection for that classic engine?

oil/fuel mixture is critical. the entire motor has been design around the fuel mixture ratio. be as accurate as possible.