It might be a bit hard to start and will keep the skeeters at bay but should have no long term effects. Wallyworld or an auto parts store may carry an inexpensive hand siphon that will get most out.

You don't need to do anything but use it. Contrary to popular belief, the engine will not smoke with a 2-cycle mix in it. This is because the 4-cycle is so much more efficient. I would not use it all the time because of possible carbon build-up, but one tank won't hurt. I, for one, deliberately use oil in my 4-cycle fuel mix - a light solvent oil like Marvel Mystery Oil at one ounce/gallon.

Don't worry about it. Maybe when the tank gets 1/2 down, refill with fresh gas to dilute it even more.

A neighbor was using his snow-blower one winter. Ran out of gas, but had to leave, so his daughter brought out a can full of gas, and filled the tank, then started it up. It went "BLOOIE", not long after that! Yep--used lawn mower gas, not snow-blower oil/gas mix!

Like everyone else said. The mower should be fine. Near the end of the season, I burn up all of my two cycle gas in the lawnmower, just to get rid of it. I dilute it with regular gas. Never had any problems. Just keep an eye on your spark plug.

My uncle put kerosene in my lawn mower once when I went on vacation. He said whats wrong with my mower, it kept running and surging and backfiring. He didn't finish mowing. I came home and drained the tank. Had a hard time starting it. It did finally run without any issues and I used it for several more years.

Saxman: I use Duckhams air cooled two stroke oil, that I bought for a Yamaha RD200 20 years ago, at 400:1 - just enough to turn the petrol blue. By the way gas is now $10 a gallon here now.

'By the way gas is now $10 a gallon here now'

WOW! Of course you guys are mostly set up for the 'village' style of life where you can walk or ride a bicycle for many errands. Here, we are trapped in the 'suburban' model where we have to drive an average of 20 miles each way to work. I have a shopping center with large grocery store within one mile, but our roads and traffic signals are not set up for bicycle safety. I would have to cross a major highway without benefit of the signal because the bicycle would not trip the detector and there is no manual switch. Thousands of cyclists are hit by vehicles every year. Its hard to figure which is the more dangerous - walking or cycling, since more pedestrians are hit than cyclists. So even though our gas is only $4, we have to use a lot of it.
Anyway, using a 'top oil' in your 4-cycle at 400:1 will help it to live many more years!
My take on the current fuel 'crisis' is that the age of gasoline and Diesel is over. I doubt if you'll even be able to buy a new internal combustion-only new car within ten years. I could tell you what will replace oil-based fuels, but of course I would have to kill you LOL. I can say that it won't be alcohol. Anyone who has been paying attention will already know what the 'mystery fuel' is. Strangely enough, Jules Verne, who predicted many modern marvels in his books, also predicted the use of this fuel 'which burns with the heat of the sun' and produces no harmful emissions. The current surge in oil prices is actually because of this new fuel. Everyone in the oil business is trying to grab as much profit as they can before the oil crash, which will be the most dangerous time in history. They know that once this is really 'out of the bag' (which it already is, but most people don't believe it) they will have lost control of this huge share of the energy market. Think about the ramifications.
But, as for our mowers, there will be plenty of fuel for many years. In time there will be very few gas stations. The new technology adapts well to large vehicles like cars and trucks, but may be too cumbersome for lawn mowers, motorcycles and small aircraft, so I expect we will be able to find fuel for our petrol mowers.

Saxman: I like your take on the oil crisis - depression looms here rapidly - our socialist government has not taken any of the economy-stimulating steps that have been taken in United States of America. I think you will come out of your recession a little more quickly than us.
I used to ride a bike to work but take the bus or train now, since I was knocked off by a lady taking her son to school in a large Mercedes 4 x 4. Funny, they always say "they never saw you".

Its hard to see annoying roadside objects when;
> you're talking to the kids
> talking on the phone
> drinking coffe
> putting on makeup
> watching a movie
> smoking a cigarette
> listening to/watching the GPS
> driving a 4500 lb vehicle at 55 mph in a 35 mph zone.

'By the way gas is now $10 a gallon here now'

Is this a joke? $10.00 ????

"My take on the current fuel 'crisis' is that the age of gasoline and Diesel is over. I doubt if you'll even be able to buy a new internal combustion-only new car within ten years. I could tell you what will replace oil-based fuels, but of course I would have to kill you LOL. I can say that it won't be alcohol. Anyone who has been paying attention will already know what the 'mystery fuel' is. Strangely enough, Jules Verne, who predicted many modern marvels in his books, also predicted the use of this fuel 'which burns with the heat of the sun' and produces no harmful emissions. The current surge in oil prices is actually because of this new fuel. Everyone in the oil business is trying to grab as much profit as they can before the oil crash, which will be the most dangerous time in history. They know that once this is really 'out of the bag' (which it already is, but most people don't believe it) they will have lost control of this huge share of the energy market. Think about the ramifications"

Just thought it was funny that there are six months left on this prediction and car lots are swimming in brand new internal combustion only vehicles and fuel prices are relatively cheap. I predict they will be around for a long time to come.

I know! I just read it for the first time in years and I was wondering what I was drinking that night!

The only problem with "going ahead and using the mower" is that after our daughter used our gas/oil mix, the mower won't start.

Replace spark plug , add fresh gas all will be fine !

Did replace spark plug and later drained the "old" gas and added new. Let it sit overnight, so we'll see this morning - thanks!!

Came here for advice on oil/gas mix in my mower, stayed for the predictions on the fall of the internal combustion engine... Saxman I'm guessing the miracle fuel you were referring to was hydrogen fuel cells? If I recall correctly, that was what everyone was predicting was going to save us from global warming 10 years ago. It really is a shame that they haven't been able to get it right yet, pro because oil companies are still pushing it down.

Reading through the comments and had to laugh about the comment four years ago about gas engines will be around for a long time. What is Tesla and the other big auto makers focused on now. It does not seem to be the conbustable engine. Are we at the tipping point?

Ok Guys.... We're talking about putting 2-stroke oil in a 4-stroke mower.... Lol Not the Oil/fuel Crisis