what happens if you put 2 stroke gas in a 4 stroke engine

You probably didn't ruin it, but that smoke is the 2-stroke oil burning off. Drain the tank completely, refill with fresh gas, and run it for a while. The oil residue will eventually burn out, but change your oil too since some may have seeped past the rings.

I did this once on a Yamaha Kodiak. It smoked like crazy for about 20 minutes then cleared up. I changed the oil and filter right after and it was fine. The 2-stroke oil can foul the spark plug, so check that too.

You might have gotten lucky if you only ran it 10 minutes. The oil in 2-stroke gas can cause carbon buildup on valves and piston rings in a 4-stroke. I'd do a compression test to be safe.

Honestly, it's not the end of the world. The 2-stroke oil just burns differently. Drain the tank, put in fresh gas, and maybe add some fuel system cleaner. Change the oil after a few hours of riding.

I'd be more worried about the spark plug getting fouled. Pull it out and see if it's black and oily. If so, clean or replace it. Also, check your air filter for any oil residue.

You should definitely change the oil. The 2-stroke oil can contaminate the crankcase oil and reduce lubrication. Use a good quality 10W-40 and run it for a short ride, then change it again.

I disagree with the people saying it's no big deal. If you rode it hard, the oil could have caused detonation or pre-ignition. I'd flush the fuel system and do an oil change before riding again.

It's a common mistake. The Rancher is tough, so it'll probably be fine. Just don't make a habit of it. Drain the tank, fill with premium gas, and take it easy for the first few miles.

Check your exhaust for excessive smoke. If it stops after a few minutes, you're good. If it keeps smoking, you might have oil in the muffler that needs to burn off. That can take a while.

I'd also recommend checking the fuel lines and carburetor if you have one. The 2-stroke oil can gum things up. A little Sea Foam in the tank can help clean it out.

You might want to pull the valve cover and inspect for any oil residue. If the 2-stroke oil got into the top end, it could cause sticky valves. Probably not, but worth a look if you're handy.

I've seen this happen on a Polaris Sportsman. The owner ran it for an hour before realizing. Ended up needing a top end rebuild because the rings got stuck. Don't risk it—do a thorough flush.

The smell is normal. That's the 2-stroke oil burning off. I'd run it at low RPM for a while to let it clear out. Then change the oil and filter. Should be back to normal.

If you have fuel injection, the injectors might get clogged from the oil. I'd add a fuel injector cleaner to the next tank. Better safe than sorry.

I think you're overthinking it. Drain the tank, put in fresh gas, and ride it. If it runs fine after 10 minutes, you're good. These engines are built to handle a little abuse.

Don't forget to check the oil level. The 2-stroke gas can dilute the oil if it gets past the rings. If the oil smells like gas, change it immediately.

I'd also inspect the spark plug wire and boot for any oil contamination. Oil can cause misfires if it gets on the plug. Clean everything with brake cleaner.

You could also run a compression test now and then again after a few hours to see if there's any change. If compression drops, you might have ring damage.

Honestly, I'd just ride it and see. If it starts and runs without issues after a few minutes, you're probably fine. But if it starts knocking or smoking heavily, shut it down and get it checked.

I partially disagree with the 'just ride it' crowd. A 10-minute run with 2-stroke gas isn't ideal, but it's not catastrophic. Do the oil change and fuel flush, then monitor it. If it runs clean, you dodged a bullet.