Performance lawn mower

yes there should. BUT you really shouldnt tip a mower on its side. If its a 4 stroke mower then theres a good chance engine oil will come up through the breather and into your air filter and carb,or into the exhaust if tipped the other way. As a rule most mowers should be tipped backwards so the spark plug is upward.

Its to stop the dust blocking the filter. The filter should be cleaned with petrol every 4 to 6 months to remove the dust & oil build up, cleaned in/with petrol and re-oiled. Its also good to clean the filter housing each time you clean the filter

You haven't supplied a lot of information but generally when this happens it is due t the mower being tipped the wrong way.
If you must look under the mower then tip it back with the handles to the ground and front wheel in the air.
Now to rectify your problem; The air-filter will probably be saturated with oil. It will probably be the cartridge type which is not serviceable. Purchase a new filter (take your old filter so the sale person can compare like for like). Before you refit the new filter, take out the sparkplug, it will probably be saturated in oil - wash it in petrol, let it dry then refit it. The engine should start and belch out great quantities of smoke. Don't be alarmed this will burn away. Once the smoke has cleared, check the oil level, fit the air filter and mow your lawn.

How does it run? Is it back firing through the air filter box area? And although your stating it is oil is it actually oil or gasoline that is black due to getting dirty? Don't shoot me! I'm going on what information I'm reading what you submitted. If oil is it enough to show up quickly on the dipstick/engine oil level ? Get back to us and we can go further.

lol too much oil bud take a little out

maybe u have to much oil in it or there mite be a stone in the carberator or petrol tank thats blocking the petrol ?

May be time for a tune up. Replace spark plug, air filter, change oil and sharpen blade. You may have some water in your gas. I would check to see where it is leaking oil. It may be the oil seal on the pto(bottom) side of the engine leaking and needs to be replaced.

I have a yardman lawn mower that is two years old. It is now blowing oil out the exhaust and also blue smoke. Any idea what is wrong?

You have overfilled the oil tank. White smoke is only a hassle, not a serious problem. You have to empty some of the oil and change the gas. Clean the air filter if it is the spongy type with Dawn Dishwashing Liquid, rinsing and drying it well before reinstalling. The white smoke will stop soon as it is still in the gas that is in the carb. If the case is that you haven't filled it with oil prior to this smoke then you must be mowing on a hillside and the gas tank was on the lower side allowing oil to leak into the gas. Same solution.

Check air filter, check screen in bottom of fuel tank,
New spark plug and also check the spark.
If there is a weak spark, the coil may need to be replaced.

If you have good spark, clean air filter, and clean fuel tank screen, then the carberator will need to be pulled of and cleaned out with solvent