I made the mistake of keeping my 2 gas cans next to each other when I first moved in to our house (first house we owned and had to take care of lawns). Wrote (2-stroke Engine Gas (50:1)" on the can with oil added. My wife put the straight gas in the weedwhacker the first time she filled it up because she said she couldn't tell the difference between the cans after she'd asked me where the gas for it was and I just said "up on the shelf." Fortunately, she was just filling it up after using it, so I could dump it. I'd just assumed everyone knew which things where 2-stroke and which were 4 stroke, so I didn't write which items were for which on the cans. Now I know.