I have been in the habit of dumping old 2 cycle oil mix in my car gas tank in small amounts.
I recently was informed by a mechanic to not do this as,even small amounts can ruin the Catalytic converter.
Thoughts?
An interesting question that I think only a chemist who makes 2-stroke oil will be able to resolve.
I would have dumped it in my gas tank without thinking twice. 2-stroke oil is made to burn without ash, so I would not have expected residue to accumulate on catalyst surfaces. However, it may have lubricity enhancers blended in at parts-per-million levels. These compounds will not need to be listed on the material safety data sheet because they are not there at high enough concentrations to be reportable.
I can think of compounds that might be used that would not be good for oxygen sensors and catalytic converters. Your mechanic may be correct. Just to be safe, I guess that if I find myself with 2-stroke oil to get rid of, I will burn it in my old 4-stroke lawn mower, not in my car.
A little bit at the time added to a full tank of gas will do no harm. 4 stroke cycle oil does not have near the additives in it that regular motor oil has (up to 28%). The oil in the gas will burn just like crankcase oil coming up past the rings will.
The secret is small doses.
What do I do with my leftover gas/oil mixture? It goes to the landfill where they have a special tank for old gasoline and diesel fuel. It gets recycled at a nearby plant.
One of the properties of 2-stroke oil is that it burns VERY cleanly. I have dumped 3 gallons of mix, which contained a half-pint of outboard oil, in a 20 gallon automotive fuel tank. The dilution ratio is now insignificant and will not harm the converter or anything else…They still sell “top-oil” which is virtually the same thing and it does no harm…
If you figure 1 quart of oil per 1000 miles is OK for a car to burn (according to most carmakers), and assume 20 mpgs, that’s 1 quart/50 gallons. Keep it under that amount, I don’t see where it would do harm (ignoring any wierd chemical additives, that is).